Problem accessing the doorbell while on the move

Hello, maybe someone can help me. we have had the Eufy Doorbell Wired for about 1 year and never had any problems. But for about 1 month we have had the problem that we cannot answer the doorbell while on the move. When we are at home, it works flawlessly via wifi. Not via LTE, only when we access the bell via VPN. Does anyone have any idea why this could be lying?

The same with my doorbell, since a few weeks, it seems it’s connecting but it stops. At home it works fine.

Same problem with my doorbell

I’m seeing the same problem recently. Support sent me a renewed doorbell to rule out the problem but it’s the same. WiFi is ok mainly seeing the problem on 4G/5G network where the live view takes long to play.