我整个上午都在排查如何通过网络管理器连接到我雇主的 VPN。我在各个网站上找到了许多支持帖子，并尝试了所有建议的方法以及各种解决方案，但都不起作用。
首先，这是尝试通过 GUI 连接到 VPN 后网络管理器的日志：
$ journalctl -u NetworkManager | tail -n 200 | less
Mar 02 10:19:15 xps NetworkManager[5170]: Starting strongSwan 5.8.2 IPsec [starter]...
Mar 02 10:19:15 xps NetworkManager[5170]: Loading config setup
Mar 02 10:19:15 xps NetworkManager[5170]: Loading conn 'e30e20a1-6f99-46d8-9e7e-2007356cff21'
Mar 02 10:19:15 xps ipsec_starter[5170]: Starting strongSwan 5.8.2 IPsec [starter]...
Mar 02 10:19:15 xps ipsec_starter[5170]: Loading config setup
Mar 02 10:19:15 xps ipsec_starter[5170]: Loading conn 'e30e20a1-6f99-46d8-9e7e-2007356cff21'
Mar 02 10:19:15 xps ipsec_starter[5221]: Attempting to start charon...
Mar 02 10:19:15 xps charon[5222]: 00[DMN] Starting IKE charon daemon (strongSwan 5.8.2, Linux 5.8.0-44-generic, x86_64)
Mar 02 10:19:15 xps charon[5222]: 00[CFG] loading ca certificates from '/etc/ipsec.d/cacerts'
Mar 02 10:19:15 xps charon[5222]: 00[CFG] loading aa certificates from '/etc/ipsec.d/aacerts'
Mar 02 10:19:15 xps charon[5222]: 00[CFG] loading ocsp signer certificates from '/etc/ipsec.d/ocspcerts'
Mar 02 10:19:15 xps charon[5222]: 00[CFG] loading attribute certificates from '/etc/ipsec.d/acerts'
Mar 02 10:19:15 xps charon[5222]: 00[CFG] loading crls from '/etc/ipsec.d/crls'
Mar 02 10:19:15 xps charon[5222]: 00[CFG] loading secrets from '/etc/ipsec.secrets'
Mar 02 10:19:15 xps charon[5222]: 00[CFG] loading secrets from '/etc/ipsec.d/ipsec.nm-l2tp.secrets'
Mar 02 10:19:15 xps charon[5222]: 00[CFG] loaded IKE secret for %any
Mar 02 10:19:15 xps charon[5222]: 00[LIB] loaded plugins: charon aesni aes rc2 sha2 sha1 md5 mgf1 random nonce x509 revocation constraints pubkey pkcs1 pkcs7 pkcs8 pkcs12 pgp dnskey sshkey pem openssl fips-prf gmp agent xcbc hmac gcm drbg attr kernel-netlink resolve socket-
default connmark stroke updown eap-mschapv2 xauth-generic counters
Mar 02 10:19:15 xps charon[5222]: 00[LIB] dropped capabilities, running as uid 0, gid 0
Mar 02 10:19:15 xps charon[5222]: 00[JOB] spawning 16 worker threads
Mar 02 10:19:15 xps ipsec_starter[5221]: charon (5222) started after 20 ms
Mar 02 10:19:15 xps charon[5222]: 05[CFG] received stroke: add connection 'e30e20a1-6f99-46d8-9e7e-2007356cff21'
Mar 02 10:19:15 xps charon[5222]: 05[CFG] added configuration 'e30e20a1-6f99-46d8-9e7e-2007356cff21'
Mar 02 10:19:16 xps charon[5222]: 10[CFG] rereading secrets
Mar 02 10:19:16 xps charon[5222]: 10[CFG] loading secrets from '/etc/ipsec.secrets'
Mar 02 10:19:16 xps charon[5222]: 10[CFG] loading secrets from '/etc/ipsec.d/ipsec.nm-l2tp.secrets'
Mar 02 10:19:16 xps charon[5222]: 10[CFG] loaded IKE secret for %any
Mar 02 10:19:16 xps charon[5222]: 11[CFG] received stroke: initiate 'e30e20a1-6f99-46d8-9e7e-2007356cff21'
Mar 02 10:19:16 xps charon[5222]: 13[IKE] initiating Main Mode IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] to 71.89.153.210
Mar 02 10:19:16 xps charon[5222]: 13[IKE] initiating Main Mode IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] to 71.89.153.210
Mar 02 10:19:16 xps charon[5222]: 13[ENC] generating ID_PROT request 0 [ SA V V V V V ]
Mar 02 10:19:16 xps charon[5222]: 13[NET] sending packet: from 10.0.1.58[500] to 71.89.153.210[500] (532 bytes)
Mar 02 10:19:16 xps charon[5222]: 14[NET] received packet: from 71.89.153.210[500] to 10.0.1.58[500] (112 bytes)
Mar 02 10:19:16 xps charon[5222]: 14[ENC] parsed ID_PROT response 0 [ SA V V ]
Mar 02 10:19:16 xps charon[5222]: 14[ENC] received unknown vendor ID: 5b:36:2b:c8:20:f6:00:07
Mar 02 10:19:16 xps charon[5222]: 14[IKE] received NAT-T (RFC 3947) vendor ID
Mar 02 10:19:16 xps charon[5222]: 14[CFG] selected proposal: IKE:3DES_CBC/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024
Mar 02 10:19:16 xps charon[5222]: 14[ENC] generating ID_PROT request 0 [ KE No NAT-D NAT-D ]
Mar 02 10:19:16 xps charon[5222]: 14[NET] sending packet: from 10.0.1.58[500] to 71.89.153.210[500] (244 bytes)
Mar 02 10:19:16 xps charon[5222]: 01[NET] received packet: from 71.89.153.210[500] to 10.0.1.58[500] (276 bytes)
Mar 02 10:19:16 xps charon[5222]: 01[ENC] parsed ID_PROT response 0 [ KE NAT-D NAT-D No V V V ]
Mar 02 10:19:16 xps charon[5222]: 01[ENC] received unknown vendor ID: 40:4b:f4:39:52:2c:a3:f6
Mar 02 10:19:16 xps charon[5222]: 01[IKE] received XAuth vendor ID
Mar 02 10:19:16 xps charon[5222]: 01[IKE] received DPD vendor ID
Mar 02 10:19:16 xps charon[5222]: 01[IKE] local host is behind NAT, sending keep alives
Mar 02 10:19:16 xps charon[5222]: 01[ENC] generating ID_PROT request 0 [ ID HASH ]
Mar 02 10:19:16 xps charon[5222]: 01[NET] sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:19:16 xps charon[5222]: 06[NET] received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (76 bytes)
Mar 02 10:19:16 xps charon[5222]: 06[IKE] queueing TRANSACTION request as tasks still active
Mar 02 10:19:20 xps charon[5222]: 07[IKE] sending retransmit 1 of request message ID 0, seq 3
Mar 02 10:19:20 xps charon[5222]: 07[NET] sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:19:20 xps charon[5222]: 09[NET] received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (92 bytes)
Mar 02 10:19:20 xps charon[5222]: 09[ENC] payload type ID_V1 was not encrypted
Mar 02 10:19:20 xps charon[5222]: 09[ENC] could not decrypt payloads
Mar 02 10:19:20 xps charon[5222]: 09[IKE] integrity check failed
Mar 02 10:19:20 xps charon[5222]: 09[ENC] generating INFORMATIONAL_V1 request 65355755 [ HASH N(INVAL_HASH) ]
Mar 02 10:19:20 xps charon[5222]: 09[NET] sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:19:20 xps charon[5222]: 09[IKE] ID_PROT response with message ID 0 processing failed
Mar 02 10:19:26 xps NetworkManager[5273]: Stopping strongSwan IPsec...
Mar 02 10:19:26 xps charon[5222]: 00[DMN] signal of type SIGINT received. Shutting down
Mar 02 10:19:26 xps charon[5222]: 00[IKE] destroying IKE_SA in state CONNECTING without notification
Mar 02 10:19:26 xps NetworkManager[5252]: initiating Main Mode IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] to 71.89.153.210
Mar 02 10:19:26 xps NetworkManager[5252]: generating ID_PROT request 0 [ SA V V V V V ]
Mar 02 10:19:26 xps NetworkManager[5252]: sending packet: from 10.0.1.58[500] to 71.89.153.210[500] (532 bytes)
Mar 02 10:19:26 xps NetworkManager[5252]: received packet: from 71.89.153.210[500] to 10.0.1.58[500] (112 bytes)
Mar 02 10:19:26 xps NetworkManager[5252]: parsed ID_PROT response 0 [ SA V V ]
Mar 02 10:19:26 xps NetworkManager[5252]: received unknown vendor ID: 5b:36:2b:c8:20:f6:00:07
Mar 02 10:19:26 xps NetworkManager[5252]: received NAT-T (RFC 3947) vendor ID
Mar 02 10:19:26 xps NetworkManager[5252]: selected proposal: IKE:3DES_CBC/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024
Mar 02 10:19:26 xps NetworkManager[5252]: generating ID_PROT request 0 [ KE No NAT-D NAT-D ]
Mar 02 10:19:26 xps NetworkManager[5252]: sending packet: from 10.0.1.58[500] to 71.89.153.210[500] (244 bytes)
Mar 02 10:19:26 xps NetworkManager[5252]: received packet: from 71.89.153.210[500] to 10.0.1.58[500] (276 bytes)
Mar 02 10:19:26 xps NetworkManager[5252]: parsed ID_PROT response 0 [ KE NAT-D NAT-D No V V V ]
Mar 02 10:19:26 xps NetworkManager[5252]: received unknown vendor ID: 40:4b:f4:39:52:2c:a3:f6
Mar 02 10:19:26 xps NetworkManager[5252]: received XAuth vendor ID
Mar 02 10:19:26 xps NetworkManager[5252]: received DPD vendor ID
Mar 02 10:19:26 xps NetworkManager[5252]: local host is behind NAT, sending keep alives
Mar 02 10:19:26 xps NetworkManager[5252]: generating ID_PROT request 0 [ ID HASH ]
Mar 02 10:19:26 xps NetworkManager[5252]: sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:19:26 xps NetworkManager[5252]: received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (76 bytes)
Mar 02 10:19:26 xps NetworkManager[5252]: queueing TRANSACTION request as tasks still active
Mar 02 10:19:26 xps NetworkManager[5252]: sending retransmit 1 of request message ID 0, seq 3
Mar 02 10:19:26 xps NetworkManager[5252]: sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:19:26 xps NetworkManager[5252]: received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (92 bytes)
Mar 02 10:19:26 xps NetworkManager[5252]: payload type ID_V1 was not encrypted
Mar 02 10:19:26 xps NetworkManager[5252]: could not decrypt payloads
Mar 02 10:19:26 xps NetworkManager[5252]: integrity check failed
Mar 02 10:19:26 xps NetworkManager[5252]: generating INFORMATIONAL_V1 request 65355755 [ HASH N(INVAL_HASH) ]
Mar 02 10:19:26 xps NetworkManager[5252]: sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:19:26 xps NetworkManager[5252]: ID_PROT response with message ID 0 processing failed
Mar 02 10:19:26 xps NetworkManager[5252]: destroying IKE_SA in state CONNECTING without notification
Mar 02 10:19:26 xps NetworkManager[5252]: establishing connection 'e30e20a1-6f99-46d8-9e7e-2007356cff21' failed
Mar 02 10:19:26 xps ipsec_starter[5221]: child 5222 (charon) has quit (exit code 0)
Mar 02 10:19:26 xps ipsec_starter[5221]:
Mar 02 10:19:26 xps ipsec_starter[5221]: charon stopped after 200 ms
Mar 02 10:19:26 xps ipsec_starter[5221]: ipsec starter stopped
Mar 02 10:19:26 xps nm-l2tp-service[5158]: g_dbus_method_invocation_take_error: assertion 'error != NULL' failed
Mar 02 10:19:26 xps NetworkManager[5096]: <info> [1614698366.5234] vpn-connection[0x55d317c68100,e30e20a1-6f99-46d8-9e7e-2007356cff21,"Company",0]: VPN plugin: state changed: stopped (6)
Mar 02 10:19:26 xps NetworkManager[5096]: <info> [1614698366.5249] manager: startup complete
Mar 02 10:19:26 xps NetworkManager[5096]: <info> [1614698366.5266] vpn-connection[0x55d317c68100,e30e20a1-6f99-46d8-9e7e-2007356cff21,"Company",0]: VPN service disappeared
Mar 02 10:19:26 xps NetworkManager[5096]: <warn> [1614698366.5282] vpn-connection[0x55d317c68100,e30e20a1-6f99-46d8-9e7e-2007356cff21,"Company",0]: VPN connection: failed to connect: 'Message recipient disconnected from message bus without replying'
似乎产生积极效果的少数修改之一是在我的 strongswan conf（/etc/strongswan.conf）中添加以下行：
accept_unencrypted_mainmode_messages = yes
这似乎解决了“无法解密有效负载”错误，并导致以下日志：
Mar 02 10:40:19 xps nm-l2tp-service[6195]: Check port 1701
Mar 02 10:40:19 xps NetworkManager[6210]: Stopping strongSwan IPsec failed: starter is not running
Mar 02 10:40:21 xps NetworkManager[6207]: Starting strongSwan 5.8.2 IPsec [starter]...
Mar 02 10:40:21 xps ipsec_starter[6207]: Starting strongSwan 5.8.2 IPsec [starter]...
Mar 02 10:40:21 xps NetworkManager[6207]: Loading config setup
Mar 02 10:40:21 xps NetworkManager[6207]: Loading conn 'e30e20a1-6f99-46d8-9e7e-2007356cff21'
Mar 02 10:40:21 xps ipsec_starter[6207]: Loading config setup
Mar 02 10:40:21 xps ipsec_starter[6207]: Loading conn 'e30e20a1-6f99-46d8-9e7e-2007356cff21'
Mar 02 10:40:21 xps ipsec_starter[6220]: Attempting to start charon...
Mar 02 10:40:21 xps charon[6221]: 00[DMN] Starting IKE charon daemon (strongSwan 5.8.2, Linux 5.8.0-44-generic, x86_64)
Mar 02 10:40:21 xps charon[6221]: 00[CFG] loading ca certificates from '/etc/ipsec.d/cacerts'
Mar 02 10:40:21 xps charon[6221]: 00[CFG] loading aa certificates from '/etc/ipsec.d/aacerts'
Mar 02 10:40:21 xps charon[6221]: 00[CFG] loading ocsp signer certificates from '/etc/ipsec.d/ocspcerts'
Mar 02 10:40:21 xps charon[6221]: 00[CFG] loading attribute certificates from '/etc/ipsec.d/acerts'
Mar 02 10:40:21 xps charon[6221]: 00[CFG] loading crls from '/etc/ipsec.d/crls'
Mar 02 10:40:21 xps charon[6221]: 00[CFG] loading secrets from '/etc/ipsec.secrets'
Mar 02 10:40:21 xps charon[6221]: 00[CFG] loading secrets from '/etc/ipsec.d/ipsec.nm-l2tp.secrets'
Mar 02 10:40:21 xps charon[6221]: 00[CFG] loaded IKE secret for %any
Mar 02 10:40:21 xps charon[6221]: 00[LIB] loaded plugins: charon aesni aes rc2 sha2 sha1 md5 mgf1 random nonce x509 revocation constraints pubkey pkcs1 pkcs7 pkcs8 pkcs12 pgp dnskey sshkey pem openssl fips-prf gmp agent xcbc hmac gcm drbg attr kernel-netlink resolve socket-
default connmark stroke updown eap-mschapv2 xauth-generic counters
Mar 02 10:40:21 xps charon[6221]: 00[LIB] dropped capabilities, running as uid 0, gid 0
Mar 02 10:40:21 xps charon[6221]: 00[JOB] spawning 16 worker threads
Mar 02 10:40:21 xps ipsec_starter[6220]: charon (6221) started after 20 ms
Mar 02 10:40:21 xps charon[6221]: 06[CFG] received stroke: add connection 'e30e20a1-6f99-46d8-9e7e-2007356cff21'
Mar 02 10:40:21 xps charon[6221]: 06[CFG] added configuration 'e30e20a1-6f99-46d8-9e7e-2007356cff21'
Mar 02 10:40:22 xps charon[6221]: 07[CFG] rereading secrets
Mar 02 10:40:22 xps charon[6221]: 07[CFG] loading secrets from '/etc/ipsec.secrets'
Mar 02 10:40:22 xps charon[6221]: 07[CFG] loading secrets from '/etc/ipsec.d/ipsec.nm-l2tp.secrets'
Mar 02 10:40:22 xps charon[6221]: 07[CFG] loaded IKE secret for %any
Mar 02 10:40:22 xps charon[6221]: 09[CFG] received stroke: initiate 'e30e20a1-6f99-46d8-9e7e-2007356cff21'
Mar 02 10:40:22 xps charon[6221]: 12[IKE] initiating Main Mode IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] to 71.89.153.210
Mar 02 10:40:22 xps charon[6221]: 12[IKE] initiating Main Mode IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] to 71.89.153.210
Mar 02 10:40:22 xps charon[6221]: 12[ENC] generating ID_PROT request 0 [ SA V V V V V ]
Mar 02 10:40:22 xps charon[6221]: 12[NET] sending packet: from 10.0.1.58[500] to 71.89.153.210[500] (532 bytes)
Mar 02 10:40:22 xps charon[6221]: 13[NET] received packet: from 71.89.153.210[500] to 10.0.1.58[500] (112 bytes)
Mar 02 10:40:22 xps charon[6221]: 13[ENC] parsed ID_PROT response 0 [ SA V V ]
Mar 02 10:40:22 xps charon[6221]: 13[ENC] received unknown vendor ID: 5b:36:2b:c8:20:f6:00:07
Mar 02 10:40:22 xps charon[6221]: 13[IKE] received NAT-T (RFC 3947) vendor ID
Mar 02 10:40:22 xps charon[6221]: 13[CFG] selected proposal: IKE:3DES_CBC/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024
Mar 02 10:40:22 xps charon[6221]: 13[ENC] generating ID_PROT request 0 [ KE No NAT-D NAT-D ]
Mar 02 10:40:22 xps charon[6221]: 13[NET] sending packet: from 10.0.1.58[500] to 71.89.153.210[500] (244 bytes)
Mar 02 10:40:22 xps charon[6221]: 14[NET] received packet: from 71.89.153.210[500] to 10.0.1.58[500] (276 bytes)
Mar 02 10:40:22 xps charon[6221]: 14[ENC] parsed ID_PROT response 0 [ KE NAT-D NAT-D No V V V ]
Mar 02 10:40:22 xps charon[6221]: 14[ENC] received unknown vendor ID: 40:4b:f4:39:52:2c:a3:f6
Mar 02 10:40:22 xps charon[6221]: 14[IKE] received XAuth vendor ID
Mar 02 10:40:22 xps charon[6221]: 14[IKE] received DPD vendor ID
Mar 02 10:40:22 xps charon[6221]: 14[IKE] local host is behind NAT, sending keep alives
Mar 02 10:40:22 xps charon[6221]: 14[ENC] generating ID_PROT request 0 [ ID HASH ]
Mar 02 10:40:22 xps charon[6221]: 14[NET] sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:40:22 xps charon[6221]: 15[NET] received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (76 bytes)
Mar 02 10:40:22 xps charon[6221]: 15[IKE] queueing TRANSACTION request as tasks still active
Mar 02 10:40:26 xps charon[6221]: 05[IKE] sending retransmit 1 of request message ID 0, seq 3
Mar 02 10:40:26 xps charon[6221]: 05[NET] sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:40:26 xps charon[6221]: 06[NET] received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (92 bytes)
Mar 02 10:40:26 xps charon[6221]: 06[ENC] parsed ID_PROT response 0 [ ID HASH N(INITIAL_CONTACT) ]
Mar 02 10:40:26 xps charon[6221]: 06[IKE] IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] established between 10.0.1.58[10.0.1.58]...71.89.153.210[71.89.153.210]
Mar 02 10:40:26 xps charon[6221]: 06[IKE] IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] established between 10.0.1.58[10.0.1.58]...71.89.153.210[71.89.153.210]
Mar 02 10:40:26 xps charon[6221]: 06[IKE] scheduling reauthentication in 10139s
Mar 02 10:40:26 xps charon[6221]: 06[IKE] maximum IKE_SA lifetime 10679s
Mar 02 10:40:26 xps charon[6221]: 06[ENC] parsed TRANSACTION request 3938256919 [ HASH CPRQ(X_TYPE X_USER X_PWD) ]
Mar 02 10:40:26 xps charon[6221]: 06[ENC] generating TRANSACTION response 3938256919 [ HASH CP ]
Mar 02 10:40:26 xps charon[6221]: 06[NET] sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:40:26 xps charon[6221]: 06[ENC] generating QUICK_MODE request 1430309094 [ HASH SA No ID ID NAT-OA NAT-OA ]
Mar 02 10:40:26 xps charon[6221]: 06[NET] sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (244 bytes)
Mar 02 10:40:26 xps charon[6221]: 08[NET] received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (172 bytes)
Mar 02 10:40:26 xps charon[6221]: 08[ENC] parsed QUICK_MODE response 1430309094 [ HASH SA No ID ID NAT-OA NAT-OA ]
Mar 02 10:40:26 xps charon[6221]: 08[CFG] selected proposal: ESP:3DES_CBC/HMAC_SHA1_96/NO_EXT_SEQ
Mar 02 10:40:26 xps charon[6221]: 08[IKE] CHILD_SA e30e20a1-6f99-46d8-9e7e-2007356cff21{1} established with SPIs c8170e4f_i 8a306b8f_o and TS 10.0.1.58/32[udp/l2f] === 71.89.153.210/32[udp/l2f]
Mar 02 10:40:26 xps charon[6221]: 08[IKE] CHILD_SA e30e20a1-6f99-46d8-9e7e-2007356cff21{1} established with SPIs c8170e4f_i 8a306b8f_o and TS 10.0.1.58/32[udp/l2f] === 71.89.153.210/32[udp/l2f]
Mar 02 10:40:26 xps charon[6221]: 08[ENC] generating QUICK_MODE request 1430309094 [ HASH ]
Mar 02 10:40:26 xps NetworkManager[6250]: initiating Main Mode IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] to 71.89.153.210
Mar 02 10:40:26 xps NetworkManager[6250]: generating ID_PROT request 0 [ SA V V V V V ]
Mar 02 10:40:26 xps NetworkManager[6250]: sending packet: from 10.0.1.58[500] to 71.89.153.210[500] (532 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: received packet: from 71.89.153.210[500] to 10.0.1.58[500] (112 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: parsed ID_PROT response 0 [ SA V V ]
Mar 02 10:40:26 xps NetworkManager[6250]: received unknown vendor ID: 5b:36:2b:c8:20:f6:00:07
Mar 02 10:40:26 xps NetworkManager[6250]: received NAT-T (RFC 3947) vendor ID
Mar 02 10:40:26 xps NetworkManager[6250]: selected proposal: IKE:3DES_CBC/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024
Mar 02 10:40:26 xps NetworkManager[6250]: generating ID_PROT request 0 [ KE No NAT-D NAT-D ]
Mar 02 10:40:26 xps NetworkManager[6250]: sending packet: from 10.0.1.58[500] to 71.89.153.210[500] (244 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: received packet: from 71.89.153.210[500] to 10.0.1.58[500] (276 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: parsed ID_PROT response 0 [ KE NAT-D NAT-D No V V V ]
Mar 02 10:40:26 xps NetworkManager[6250]: received unknown vendor ID: 40:4b:f4:39:52:2c:a3:f6
Mar 02 10:40:26 xps NetworkManager[6250]: received XAuth vendor ID
Mar 02 10:40:26 xps NetworkManager[6250]: received DPD vendor ID
Mar 02 10:40:26 xps NetworkManager[6250]: local host is behind NAT, sending keep alives
Mar 02 10:40:26 xps NetworkManager[6250]: generating ID_PROT request 0 [ ID HASH ]
Mar 02 10:40:26 xps NetworkManager[6250]: sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (76 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: queueing TRANSACTION request as tasks still active
Mar 02 10:40:26 xps NetworkManager[6250]: sending retransmit 1 of request message ID 0, seq 3
Mar 02 10:40:26 xps NetworkManager[6250]: sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (92 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: parsed ID_PROT response 0 [ ID HASH N(INITIAL_CONTACT) ]
Mar 02 10:40:26 xps NetworkManager[6250]: IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] established between 10.0.1.58[10.0.1.58]...71.89.153.210[71.89.153.210]
Mar 02 10:40:26 xps NetworkManager[6250]: scheduling reauthentication in 10139s
Mar 02 10:40:26 xps NetworkManager[6250]: maximum IKE_SA lifetime 10679s
Mar 02 10:40:26 xps NetworkManager[6250]: parsed TRANSACTION request 3938256919 [ HASH CPRQ(X_TYPE X_USER X_PWD) ]
Mar 02 10:40:26 xps NetworkManager[6250]: generating TRANSACTION response 3938256919 [ HASH CP ]
Mar 02 10:40:26 xps NetworkManager[6250]: sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (68 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: generating QUICK_MODE request 1430309094 [ HASH SA No ID ID NAT-OA NAT-OA ]
Mar 02 10:40:26 xps NetworkManager[6250]: sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (244 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (172 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: parsed QUICK_MODE response 1430309094 [ HASH SA No ID ID NAT-OA NAT-OA ]
Mar 02 10:40:26 xps charon[6221]: 08[NET] sending packet: from 10.0.1.58[4500] to 71.89.153.210[4500] (60 bytes)
Mar 02 10:40:26 xps NetworkManager[6250]: selected proposal: ESP:3DES_CBC/HMAC_SHA1_96/NO_EXT_SEQ
Mar 02 10:40:26 xps NetworkManager[6250]: CHILD_SA e30e20a1-6f99-46d8-9e7e-2007356cff21{1} established with SPIs c8170e4f_i 8a306b8f_o and TS 10.0.1.58/32[udp/l2f] === 71.89.153.210/32[udp/l2f]
Mar 02 10:40:26 xps NetworkManager[6250]: generating QUICK_MODE request 1430309094 [ HASH ]
Mar 02 10:40:26 xps NetworkManager[6250]: connection 'e30e20a1-6f99-46d8-9e7e-2007356cff21' established successfully
Mar 02 10:40:26 xps charon[6221]: 07[NET] received packet: from 71.89.153.210[4500] to 10.0.1.58[4500] (84 bytes)
Mar 02 10:40:26 xps charon[6221]: 07[ENC] parsed INFORMATIONAL_V1 request 4257504994 [ HASH D ]
Mar 02 10:40:26 xps charon[6221]: 07[IKE] received DELETE for IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1]
Mar 02 10:40:26 xps charon[6221]: 07[IKE] deleting IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] between 10.0.1.58[10.0.1.58]...71.89.153.210[71.89.153.210]
Mar 02 10:40:26 xps charon[6221]: 07[IKE] deleting IKE_SA e30e20a1-6f99-46d8-9e7e-2007356cff21[1] between 10.0.1.58[10.0.1.58]...71.89.153.210[71.89.153.210]
Mar 02 10:40:26 xps NetworkManager[6296]: Stopping strongSwan IPsec...
Mar 02 10:40:26 xps charon[6221]: 00[DMN] signal of type SIGINT received. Shutting down
Mar 02 10:40:26 xps ipsec_starter[6220]: child 6221 (charon) has quit (exit code 0)
Mar 02 10:40:26 xps ipsec_starter[6220]:
Mar 02 10:40:26 xps ipsec_starter[6220]: charon stopped after 200 ms
Mar 02 10:40:26 xps ipsec_starter[6220]: ipsec starter stopped
Mar 02 10:40:26 xps nm-l2tp-service[6195]: g_dbus_method_invocation_take_error: assertion 'error != NULL' failed
Mar 02 10:40:26 xps NetworkManager[6090]: <info> [1614699626.7743] vpn-connection[0x558f0fafe0f0,e30e20a1-6f99-46d8-9e7e-2007356cff21,"Company",0]: VPN plugin: state changed: stopped (6)
Mar 02 10:40:26 xps NetworkManager[6090]: <info> [1614699626.7816] vpn-connection[0x558f0fafe0f0,e30e20a1-6f99-46d8-9e7e-2007356cff21,"Company",0]: VPN service disappeared
Mar 02 10:40:26 xps NetworkManager[6090]: <warn> [1614699626.7855] vpn-connection[0x558f0fafe0f0,e30e20a1-6f99-46d8-9e7e-2007356cff21,"Company",0]: VPN connection: failed to connect: 'Message recipient disconnected from message bus without replying'
这一切都是在使用以下设置进行 VPN 连接时进行的：
Enable IPsec tunnel to L2TP host
Using a PSK
Using MSCHAPv2 for auth
使用：
Ubuntu 20.04.2
Network Manager v1.22.10
xl2tp v1.3.12
ipsec/strongswan U5.8.2/K5.8.0-44-generic
我也尝试过使用 ike-scan 来查看服务器使用了哪些 phase1/phase2 算法，但是手动将它们设置为正确的值（第 1 阶段为 '3des-sha1-modp1024'，第 2 阶段为 '3des-sha1'）似乎没有什么区别。
如能得到任何帮助解决这个问题，我们将不胜感激！