Actually I'm not 100% sure that my issue has to do with a recent Ubuntu update (changed from 23.04 to 23.10) but it's most likely. The device (running on Ubuntu 23.10) appears offline for all other devices (currently 5 in total). As far as I can see the Resilio Sync Service is running.
resilio-sync.service - Resilio Sync service
Loaded: loaded (/usr/lib/systemd/user/resilio-sync.service; enabled; preset: enabled)
Active: active (running) since Thu 2023-11-09 12:18:33 CET; 16min ago
also it seems that the Device is listening on some Sync relevant ports.
tcp LISTEN 0 10 127.0.0.1:8888 0.0.0.0:* users:(("rslsync",pid=2280,fd=41))
tcp LISTEN 0 10 0.0.0.0:19808 0.0.0.0:* users:(("rslsync",pid=2280,fd=32))
nevertheless I'm also not able to connect to the WebGUI.
Any hints are much appreciated.
Regards