Are both of them up to date with the latest firmware?
I have a sneaking suspicion it’s interference with someone else’s WiFi. Are you able to manually change the channel In your router that your WiFi uses?
Does it happen randomly, or at similar times during the day? Both go offline at the same time?
What kind of router do you have? Have you checked to see if it needs a firmware update? If you are familiar with a program called Wireshark, this can help identify connection issues. Such as if the packet going fro your Grobo to their server 1. Makes it to the router, 2. If there is a successful handshake & connection established, 3. If the packet makes it to the server, you will see an ack reply from their server, 4. If there is an error within the contents of the packet, 5. If the connection request to their server times out.
Only a small amount of things you can find out from Wireshark. Oh, it’s also 100% free open source.
A word of advice before using it. If you are on a corporate WiFi, they probably have intrusion detection software and hardware in place which will flag Wireshark as hostile. When I was in college we’d screw with the director of the schools IT and turn Wireshark on while we were connected to the schools WiFi. He didn’t like having to trek over to our classroom (he always knew it was us).