I’ve been happily using Synchting (via Synctrazor) for many months to sync a home laptop with an office computer. I’ve turned a home laptop and remote (office-based) desktop on today and each one is saying the other is disconnected.
According to Syncthing, Both devices were last seen yesterday at 16:05, though both were on until 20:00 yesterday. I only noticed nothing has synced around 12:00 PM today.
I made no changes to either machine yesterday and was using the desktop at 16:05 yesterday - when both were last connected.
I have only just started using ST again, so I do not really know my way around, and I am not familiar with Synctrazor. Sometimes if I cannot access the webpage it is because synthing.exe is not running. I am sure you have rebooted both computers, but you may also wish to reboot both routers as sometimes specific ports can get locked, so this would be easy to rule out. (I think ST may use dynamic ports by default if such a thing is possible, but there is no harm investigating this aspect).