I use the LAN connection for data offloading. This means that the M1 goes to the web via LAN instead of via SIM card. This saves data volume.

As I have also read in Forum Netgear, M1 does not have this feature

Can I also connect the LAN output to an existing router and switch off the WLAN in the M1 or M2? I.e. use the Netgear only as a modem? I would like to slowly get away from Swisscom and UPC.....

I have several M1s in use, all of which have a switch with several terminals connected.
Tip for buying: wait for a special offer, or buy the M2, which can handle 5G.