Bearer MTU not recognised by NetworkManager

Thu May 7 13:43:51 UTC 2020

Hi,

I’m observing that NetworkManager (v1.20.2) does not recognise the MTU (=1360) exposed by the ModemManager’s (v1.10.6) bearer object and instead uses some default value (=1500). This seems to lead to issues which are fixed when manually setting the MTU to a lower value. When checking the NetworkManager’s connection settings, gsm.mtu is set to “auto". I’m observing this on a Quectel BG96 hooked up via QMI. My kernel version is 4.19.87.

Is this a known issue? Is anyone aware whether this is fixed upstream?

Thanks,
Sven