mosh login to server stops right after showing the /etc/issue or says no data received or exit right away

mosh 1.3.2 [build mosh 1.3.2]
both server and client are Ubuntu 22.04
firewall ports for 60000:61000 are opened both input output and on both machine.
nc can connect through.
Also the login shows the server's /etc/issue content.
ssh has no problem.
Is there a log can be checked to see what's going on?

here's the auth.log on the server side

Apr 12 00:14:23 hostn sshd[1793727]: Connection from 125.92.1.2 port 54704 on 10.0.0.212 port 1022 rdomain ""
Apr 12 00:14:23 hostn sshd[1793727]: Accepted key RSA SHA256:sha256keystring/QRmk/sha256keystring222 found at /home/userxx/.ssh/authorized_keys:4
Apr 12 00:14:23 hostn sshd[1793727]: Postponed publickey for userxx from 125.92.1.2 port 54704 ssh2 [preauth]
Apr 12 00:14:23 hostn sshd[1793727]: Accepted key RSA SHA256:sha256keystring/QRmk/sha256keystring222 found at /home/userxx/.ssh/authorized_keys:4
Apr 12 00:14:23 hostn sshd[1793727]: Accepted publickey for userxx from 125.92.1.2 port 54704 ssh2: RSA SHA256:sha256keystring/QRmk/sha256keystring222
Apr 12 00:14:23 hostn sshd[1793727]: pam_unix(sshd:session): session opened for user userxx(uid=1001) by (uid=0)
Apr 12 00:14:23 hostn systemd-logind[850]: New session 4034 of user userxx.
Apr 12 00:14:23 hostn sshd[1793727]: User child is on pid 1793732
Apr 12 00:14:23 hostn sshd[1793732]: Starting session: command on pts/1 for userxx from 125.92.1.2 port 54704 id 0
Apr 12 00:14:23 hostn sshd[1793732]: Received disconnect from 125.92.1.2 port 54704:11: disconnected by user
Apr 12 00:14:23 hostn sshd[1793732]: Disconnected from user userxx 125.92.1.2 port 54704
Apr 12 00:14:23 hostn sshd[1793727]: pam_unix(sshd:session): session closed for user userxx
Apr 12 00:14:23 hostn systemd-logind[850]: Removed session 4034.
Apr 12 00:14:34 hostn sudo:   userxx : TTY=pts/0 ; PWD=/var/log ; USER=root ; COMMAND=/usr/bin/cat auth.log
Apr 12 00:14:34 hostn sudo: pam_unix(sudo:session): session opened for user root(uid=0) by userxx(uid=1001)
Apr 12 00:14:34 hostn sudo: pam_unix(sudo:session): session closed for user root
Apr 12 00:14:59 hostn sshd[1793807]: Connection from 125.92.1.2 port 58408 on 10.0.0.212 port 1022 rdomain ""
Apr 12 00:14:59 hostn sshd[1793807]: Accepted key RSA SHA256:sha256keystring/QRmk/sha256keystring222 found at /home/userxx/.ssh/authorized_keys:4
Apr 12 00:14:59 hostn sshd[1793807]: Postponed publickey for userxx from 125.92.1.2 port 58408 ssh2 [preauth]
Apr 12 00:14:59 hostn sshd[1793807]: Accepted key RSA SHA256:sha256keystring/QRmk/sha256keystring222 found at /home/userxx/.ssh/authorized_keys:4
Apr 12 00:14:59 hostn sshd[1793807]: Accepted publickey for userxx from 125.92.1.2 port 58408 ssh2: RSA SHA256:sha256keystring/QRmk/sha256keystring222
Apr 12 00:14:59 hostn sshd[1793807]: pam_unix(sshd:session): session opened for user userxx(uid=1001) by (uid=0)
Apr 12 00:14:59 hostn systemd-logind[850]: New session 4035 of user userxx.
Apr 12 00:14:59 hostn sshd[1793807]: User child is on pid 1793812
Apr 12 00:14:59 hostn sshd[1793812]: Starting session: command on pts/1 for userxx from 125.92.1.2 port 58408 id 0
Apr 12 00:14:59 hostn sshd[1793812]: Received disconnect from 125.92.1.2 port 58408:11: disconnected by user
Apr 12 00:14:59 hostn sshd[1793812]: Disconnected from user userxx 125.92.1.2 port 58408
Apr 12 00:14:59 hostn sshd[1793807]: pam_unix(sshd:session): session closed for user userxx
Apr 12 00:14:59 hostn systemd-logind[850]: Removed session 4035.

on the client side, I don't find useful information

No source files or tests are identified. Start by reproducing the login failure on Ubuntu 22.04 with the reported mosh, SSH, firewall, and port conditions, then inspect client and server logs around the immediate disconnect. Done means identifying the cause of the session ending after authentication and documenting or fixing it.