We had a power issue at one of our sites. I've replaced the UPS. Everything was down. Axxess system, switches, router all powered off.

Replaced the UPS turned everything on and now the Axxess system can't IC any other node. I can ping it and connect to DBManager but can't talk to any other sites. I tested pinging it from offsite as well and the other nodes can ping it.

Confirm your node programming on the system. If any of core devices are set to DHCP, you're probably having an addressing issue.