我最近升级到了 Ubuntu 18.04，现在无法连接到我的大学互联网网络。
这是我的系统日志的一个示例：
May 12 10:22:29 arian-Lenovo NetworkManager[1149]: <info> [1526104349.9518] device (wlp2s0): supplicant interface state: disconnected -> scanning
May 12 10:22:30 arian-Lenovo wpa_supplicant[1128]: wlp2s0: SME: Trying to authenticate with 4c:5e:0c:12:d3:09 (SSID='Pardise olum' freq=2432 MHz)
May 12 10:22:30 arian-Lenovo kernel: [ 4662.039374] wlp2s0: authenticate with 4c:5e:0c:12:d3:09
May 12 10:22:30 arian-Lenovo NetworkManager[1149]: <info> [1526104350.9092] device (wlp2s0): supplicant interface state: scanning -> authenticating
May 12 10:22:30 arian-Lenovo kernel: [ 4662.059006] wlp2s0: send auth to 4c:5e:0c:12:d3:09 (try 1/3)
May 12 10:22:30 arian-Lenovo wpa_supplicant[1128]: wlp2s0: Trying to associate with 4c:5e:0c:12:d3:09 (SSID='Pardise olum' freq=2432 MHz)
May 12 10:22:30 arian-Lenovo kernel: [ 4662.088856] wlp2s0: authenticated
May 12 10:22:30 arian-Lenovo kernel: [ 4662.090537] wlp2s0: associate with 4c:5e:0c:12:d3:09 (try 1/3)
May 12 10:22:30 arian-Lenovo NetworkManager[1149]: <info> [1526104350.9440] device (wlp2s0): supplicant interface state: authenticating -> associating
May 12 10:22:30 arian-Lenovo wpa_supplicant[1128]: wlp2s0: Associated with 4c:5e:0c:12:d3:09
May 12 10:22:30 arian-Lenovo wpa_supplicant[1128]: wlp2s0: CTRL-EVENT-CONNECTED - Connection to 4c:5e:0c:12:d3:09 completed [id=0 id_str=]
May 12 10:22:30 arian-Lenovo wpa_supplicant[1128]: bgscan simple: Failed to enable signal strength monitoring
May 12 10:22:30 arian-Lenovo wpa_supplicant[1128]: wlp2s0: CTRL-EVENT-SUBNET-STATUS-UPDATE status=0
May 12 10:22:30 arian-Lenovo kernel: [ 4662.108452] wlp2s0: RX AssocResp from 4c:5e:0c:12:d3:09 (capab=0x401 status=0 aid=15)
May 12 10:22:30 arian-Lenovo kernel: [ 4662.108706] wlp2s0: associated
May 12 10:22:30 arian-Lenovo NetworkManager[1149]: <info> [1526104350.9643] device (wlp2s0): supplicant interface state: associating -> completed
May 12 10:22:30 arian-Lenovo NetworkManager[1149]: <info> [1526104350.9643] device (wlp2s0): Activation: (wifi) Stage 2 of 5 (Device Configure) successful. Connected to wireless network 'Pardise olum'.
May 12 10:22:30 arian-Lenovo NetworkManager[1149]: <info> [1526104350.9649] device (wlp2s0): state change: config -> ip-config (reason 'none', sys-iface-state: 'managed')
May 12 10:22:30 arian-Lenovo NetworkManager[1149]: <info> [1526104350.9656] dhcp4 (wlp2s0): activation: beginning transaction (timeout in 45 seconds)
May 12 10:22:30 arian-Lenovo NetworkManager[1149]: <info> [1526104350.9683] dhcp4 (wlp2s0): dhclient started with pid 12765
May 12 10:22:31 arian-Lenovo dhclient[12765]: DHCPDISCOVER on wlp2s0 to 255.255.255.255 port 67 interval 3 (xid=0x9fee883f)
May 12 10:22:32 arian-Lenovo avahi-daemon[1137]: Joining mDNS multicast group on interface wlp2s0.IPv6 with address fe80::f6e9:5f14:bb32:e8e4.
May 12 10:22:32 arian-Lenovo avahi-daemon[1137]: New relevant interface wlp2s0.IPv6 for mDNS.
May 12 10:22:32 arian-Lenovo avahi-daemon[1137]: Registering new address record for fe80::f6e9:5f14:bb32:e8e4 on wlp2s0.*.
May 12 10:22:33 arian-Lenovo dhclient[12765]: DHCPDISCOVER on wlp2s0 to 255.255.255.255 port 67 interval 8 (xid=0x9fee883f)
May 12 10:22:41 arian-Lenovo dhclient[12765]: DHCPDISCOVER on wlp2s0 to 255.255.255.255 port 67 interval 7 (xid=0x9fee883f)
May 12 10:22:48 arian-Lenovo dhclient[12765]: DHCPDISCOVER on wlp2s0 to 255.255.255.255 port 67 interval 16 (xid=0x9fee883f)
May 12 10:22:54 arian-Lenovo org.gnome.Shell.desktop[2229]: Window manager warning: Buggy client sent a _NET_ACTIVE_WINDOW message with a timestamp of 0 for 0x3600084 (*syslog (/)
May 12 10:23:04 arian-Lenovo dhclient[12765]: DHCPDISCOVER on wlp2s0 to 255.255.255.255 port 67 interval 12 (xid=0x9fee883f)
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <warn> [1526104396.0041] dhcp4 (wlp2s0): request timed out
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.0042] dhcp4 (wlp2s0): state changed unknown -> timeout
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.0202] dhcp4 (wlp2s0): canceled DHCP transaction, DHCP client pid 12765
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.0202] dhcp4 (wlp2s0): state changed timeout -> done
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.0206] device (wlp2s0): state change: ip-config -> failed (reason 'ip-config-unavailable', sys-iface-state: 'managed')
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.0211] manager: NetworkManager state is now DISCONNECTED
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <warn> [1526104396.0217] device (wlp2s0): Activation: failed for connection 'Pardise olum'
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.0228] device (wlp2s0): state change: failed -> disconnected (reason 'none', sys-iface-state: 'managed')
May 12 10:23:16 arian-Lenovo avahi-daemon[1137]: Withdrawing address record for fe80::f6e9:5f14:bb32:e8e4 on wlp2s0.
May 12 10:23:16 arian-Lenovo avahi-daemon[1137]: Leaving mDNS multicast group on interface wlp2s0.IPv6 with address fe80::f6e9:5f14:bb32:e8e4.
May 12 10:23:16 arian-Lenovo avahi-daemon[1137]: Interface wlp2s0.IPv6 no longer relevant for mDNS.
May 12 10:23:16 arian-Lenovo kernel: [ 4707.173250] wlp2s0: deauthenticating from 4c:5e:0c:12:d3:09 by local choice (Reason: 3=DEAUTH_LEAVING)
May 12 10:23:16 arian-Lenovo wpa_supplicant[1128]: wlp2s0: CTRL-EVENT-DISCONNECTED bssid=4c:5e:0c:12:d3:09 reason=3 locally_generated=1
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <warn> [1526104396.0426] sup-iface[0x5591b8125a40,wlp2s0]: connection disconnected (reason -3)
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.0441] device (wlp2s0): supplicant interface state: completed -> disconnected
May 12 10:23:16 arian-Lenovo wpa_supplicant[1128]: wlp2s0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
May 12 10:23:16 arian-Lenovo gnome-shell[1437]: An active wireless connection, in infrastructure mode, involves no access point?
May 12 10:23:16 arian-Lenovo wpa_supplicant[1128]: wlp2s0: CTRL-EVENT-REGDOM-CHANGE init=USER type=COUNTRY alpha2=IR
May 12 10:23:16 arian-Lenovo gnome-shell[2229]: An active wireless connection, in infrastructure mode, involves no access point?
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.9857] policy: auto-activating connection 'arian'
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.9869] device (wlp2s0): Activation: starting connection 'arian' (37a91a54-74b3-4e9b-a729-461ba0538fca)
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.9871] device (wlp2s0): state change: disconnected -> prepare (reason 'none', sys-iface-state: 'managed')
May 12 10:23:16 arian-Lenovo NetworkManager[1149]: <info> [1526104396.9873] manager: NetworkManager state is now CONNECTING
我该如何修复此问题？