I was not getting mobile data while at #DebConf25 (Brest, France) on #Librem5. My home network is vi India. Another provider airtel worked, and the same Vi sim worked on an android phone as well as pinephone pro running mobian. On #FLX1 also vi failed but airtel worked.
I manged to get it working after installing a patched ModemManager that uses ppp instead of qmi for data connection. Thanks to @dos for maintaining these patches https://source.puri.sm/sebastian.krzyszkowiak/ModemManager/-/commits/bearers