On Thu, 18 Mar 2021, Louis Guillaume wrote:
It does show the sshd sending an unexpected "RST" packet right before the end, though...192.168.1.2.22 > 192.168.1.126.64517: Flags [R], cksum 0xbd47 ... which leads me to think it's something with sshd now.
Can you temporarily disable the firewall and do the ssh/nc tests? Stop sshd, then run it like this and post the log file (redact sensitive stuff using XXXX): /usr/sbin/sshd -E /tmp/sshd.log.txt -ddd -RVP