Bridge mode not working

Hello everyone!

I have a  O2 Home M 100 Flex prepaid sim. I want to use my ZTE G5TS as a modem only (bridge mode) and a Xiaomi Mi AIot AX3600 with openwrt as main router.

My problem is that ZTE doesn't passtrhough WAN IP to the Xiaomi.

I read on an LTE forum that changing subnet of the gateway should fix bridge mode. I changed subnet of ZTE, no luck. Reverted back. Changed subnet of Xiaomi, no luck. Tried default, no luck.

My Setup:

ZTE - Network Mode - Wireless (reffering to 5g networ) + Bridge mode

          No DHCP

          Wi-Fi off

          In bridge mode, no settings for NAT or anything else to turn off.

Xiaomi: WAN port on DHCP

I also have a Huawei WiFi6 AX3 with stock firmware. Same thing happens. WAN to DHCP, no internet, no wan ip, no connection. If i set WAN port to static ip an give it the ip 192.168.0.2 works = double NAT.

The only way this setup works, is if set Xiaomi WAN port to static and give it the 192.168.0.2 ip (zte uses 192.168.0.1). This is double NAT. I don't want double NAT.

Did I missconfigured something?

Is the ZTE router the coulprit?

Is it something that depends on O2?

ZTE → https://imgur.com/a/Glr8ruc

Xiaomi → https://imgur.com/a/BmaXXZb

If you need any details, logs, etc. let me know

Thank you for your time in advance!!