ZTE 5103e 5G issue Germany

Good day,

I hope you can help me.

I have two Zyxel 5103e 5G routers with 3 branding.

Both only use LTE when in use and I can't understand it. Why is that?

I have two o2 unlimited Max tariffs. On my Xiaomi 11T pro and my ZTE 801a 5G router I can easily use o2 5G standalone on band n28 with 700MHz. However, not on the two Zyxels, which supported 5G standalone on n28. I can rule out a weak 5g signal. Telekom 5G NSA works without any problems. I use the latest b15 Firmware and it does not matter if i select the Band use only 5G standalone or have everything on auto. Both Routers wont connect. I have a friend having same issues with that model.

Cheers, Henrik