Hello @kr0815,
the whole Victron setup works without internet access or cloud access, as long as you don’t add or program anything that requires a data connection to the outside world.
Shellys and the Android GX Display also run on the local LAN and don’t need the internet.
The Cerbo stores the log data temporarily and automatically uploads it to the VRM Portal when it comes back online.
If the router is powered on but has no internet connection, it should continue to work as before.
The alternative is an LTE stick in the router or something similar.