Hello, while this has been mentioned in one or the other thread regarding certain scenarios where Quectel or SDX55 based modems fail to register on certain networks where the MediaTek ones can (e.g. T700), I cannot find a clear conclusion whether the modem in the Chateau can be easily swapped or not.

Reason for me is that the Quectel RM502Q doesn't seem to support carrier aggregation with 5G bands. At least in conjunction with O2 Germany, I only got n78 used plus 4 LTE Bands while a UK import of the ZTE MC888 was capable of using at least n78+n28, resulting in higher average throughputs.

Hence I wonder whether one can easily swap and use some Fibocom, SIMCom or other M.2 slot - based card in that router.

Just seen this post and wondered if you did upgrade the modem?

I have a Chateau 5G AX and have just ordered a SIMcom 8262E modem, which is SDX62, in order to use 5GCA with low and high 5G bands (n1 & n78 in my case) which the SDX55 modems can't support. The modem is on the Mikrotik peripherals list so I'm assuming (hoping) it works without any issue.