I installed my RUT240 yesterday like this:
- filled in custom APN and password
- did a firmware update 07.01.4
-changed Wifi SSID and password
- changed the order in the WAN properties and put mobile on position 1
After that I rebooted the router and it worked just fine. Half an hour later I could connect to the wifi but it had no internet connection. It worked again after I restarted the router. This happenend several times.
Also: When I did not have internet connection I wanted to access the admin. But after I clicked on "mobile" in the admin it didn't load and I lost wifi connection. This occured also several times.
I am in a place with a strong 4G connection and I am really close to the router so the wifi connection is also strong.
Thanks for your help! :)