For me it doesn’t matter which sim is activated. If only eSim is activated the app works. If only the physical sim is activated, the app works. If both sims are activated, the app doesn’t work - No connection possible.
Issue in short:
- On my local Wi-Fi : Eufy security app works fine.
- On someone else Wi-Fi : Eufy security app works fine.
- My cellular connection with ONE sim active (not connected to Wifi): Eufy security app works fine.
- My cellular connection with both sim active (not connected to Wifi): Eufy security app does not work - No connection available.
I’ve had contact with Eufy about this issue. Below their reply… I’m not sure if they really do understand the issue …or take the issue seriously 
Dear,
Thanks for your reply and for your cooperation in trying the troubleshooting methods.
Please know that once we receive the feedback from our customers, we have tested it right away, the streaming works fine.
Our devices run only via the internet, but not related to the operation of the sim card since streaming is fine when one line is active and via wifi.
Maybe there is a factor with the sim card that affected the streaming performance. Although I do hope I can help you resolve the issue, I’m so sorry that there is no perfect solution now.
Sorry and apologize for the inconvenience caused.
Thank you so much for your support. Please let us know if you have any further requests!
Kind regards,