I just ran up against an issue as noted in the title and wanted to post the solution here in case anyone has this problem in the future.
Just a couple of days ago I decided to try to update my home wifi with a mesh system. Seeing as I already had an ASUS router I figured I would stick with that brand. So I bought a new faster router and installed it as my main router re-using the original router IP address and using my original main router as a mesh node.
Today I noticed my device trackers weren’t updating. Looking in the HA log I kept seeing something to effect of “SSH error. no connection to the host” (I wish I would have thought to copy it down before I fixed the problem).
I could log in with putty just fine so I figured it had to be something with HA.
After searching around it dawned on me that I could console into the docker container running HA and see if I could SSH into the router from there.
I ran “ssh -l finity 192.168.1.1” and got an error saying I couldn’t log in because there was a change in the host key. The error message gave me the command to use to delete the old key:
ssh_keygen -f “/root/.ssh/known_hosts”-R 192.168.1.1
Once I did that and restarted HA then everything started working again.
Phew!
Hope this helps someone.