Hello
I have it together with an LTE/4G router from Huawei. Works perfectly.
Sunrise uses FritzBox. This was also mentioned as compatible in the descriptions on the Internet.

Sunrise Internet Box and Deco Mesh work together without any problems. My parents got my Deco P7 and everything works perfectly. However, you must note the following, as the Deco Mesh routers have their own DHCP server, you should only connect the main Deco to the Sunrise Internet Box or any other router, as otherwise you will use two different IP address ranges, the Sunrise Box or another router also have a DHCP server. Solution: get a 5 or 8 port Ethernet switch, available from about 25 Swiss francs, then connect the first Deco to the router or modem, plug the switch into the second Deco Ethernet port and also connect the additional devices to the externally purchased switch.