我正在使用 FileZilla 通过 PPK 文件连接我的 Ubuntu 服务器，但每次我都会收到以下错误。昨天它可以正常工作，但今天我尝试了几次，但没有工作。
我检查了我的 SSH，它运行正常。知道我为什么会收到此错误吗？
Jun 20 09:44:45 ip-172-31-11-146 sshd[11731]: Disconnected from invalid user web 136.232.79.200 port 53030 [preauth]
Jun 20 09:46:15 ip-172-31-11-146 sshd[11735]: Received disconnect from 136.232.79.200 port 49450:11: Bye Bye [preauth]
Jun 20 09:46:15 ip-172-31-11-146 sshd[11735]: Disconnected from authenticating user root 136.232.79.200 port 49450 [preauth]
Jun 20 09:47:46 ip-172-31-11-146 sshd[11740]: Received disconnect from 136.232.79.200 port 45870:11: Bye Bye [preauth]
Jun 20 09:47:46 ip-172-31-11-146 sshd[11740]: Disconnected from authenticating user root 136.232.79.200 port 45870 [preauth]
Jun 20 09:48:09 ip-172-31-11-146 sshd[11743]: Accepted publickey for ubuntu from 110.226.182.195 port 10158 ssh2: RSA SHA256:zNWtw9O0p3iA02JAB8B3PB8DKDO37TtmCPDfo5he/gE
Jun 20 09:48:09 ip-172-31-11-146 sshd[11743]: pam_unix(sshd:session): session opened for user ubuntu by (uid=0)
Jun 20 09:48:09 ip-172-31-11-146 systemd-logind[483]: New session 69 of user ubuntu.
Jun 20 09:48:09 ip-172-31-11-146 systemd: pam_unix(systemd-user:session): session opened for user ubuntu by (uid=0)
Jun 20 09:48:31 ip-172-31-11-146 sudo: ubuntu : TTY=pts/0 ; PWD=/home/ubuntu ; USER=root ; COMMAND=/usr/bin/nano /var/log/auth.log
Jun 20 09:48:31 ip-172-31-11-146 sudo: pam_unix(sudo:session): session opened for user root by ubuntu(uid=0)