This is what I did to get MMS working:
- Search online for “my carrier name MMS setup APN”
- Find the APN (Access Point Name). For me it was “telenor.smart”
- On the librem 5 go to settings -> mobile -> Access point names -> Press the “+” sign in top right to add a new one.
- Insert a name of your choosing and the APN address you found in step 2. I just used the same in both fields “telenor.smart”
After this MMS worked in chatty