Most of our customers have TP-Link routers, which are 192.168.0.0/24 by default, so the 192.168.1.1 gateway the CPE has is conflicting.
Bridge mode is advantageous here, but seems to not be recommended/usable from BaiCells support, so we haven’t tried it.
What we did do was change the network on the CPE to 192.168.15.0. Having 2 routers directly behind each other both at 192.168.1.1 is likely to cause numerous issues