reboot problem

[sdjf]

Can you test the power between TP1-TP2 to make sure it is between 4.75-5.25 to make sure the power supply is working properly and your power supply is not dipping too low or going to high?

There was a similar question in another Pi forum, where pepedog mentioned that ssh had moved, if any of the scripts or systemd service files that access ssh are not looking in the right place for it, that could also explain your problems.