I did an update via the app on my iPad. After this I only see the half circle with the moving stripes but nothing else happens. I also tried the app on my iPhone but I get the same issue. I run Roon via a NOC but did not have this issue before. I also tried to reinstall the app but this did not solve the problen either.
Describe your network setup
I use a Sagemcom modem/router model F3896LG-ZG and an Intel NUC8BEH. In some of the bedrooms I have devolo wLan extenders.
Welcome to the forum! Can you please try to perform a full reboot of your networking gear and ROCK (power off, unplug 30s, plug back in)? Does that help re-establish the connectivity?
If that does not work, can you connect your Roon app to the modem instead of the extenders (temporarily unplug extenders), does that allow a connection?