[SRU] network-manager can’t modify MTU automatically based on what ModemManager exposes for WWAN modems.
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
network-manager (Ubuntu) |
Fix Released
|
Medium
|
Unassigned | ||
Focal |
Fix Released
|
Medium
|
Unassigned |
Bug Description
[Impact]
Some 4G/5G mobile networks(for ex., AT&T) requires a specific MTU setting, this setting will be exposed by the ModemManager for network-manger to configure the MTU of the modem network interface .
The current network-manager v1.22.10-1ubuntu2.2 in focal can’t pass AT&T’s modem system certification.
[Fix]
This upstream patch can resolve this bug: https:/
[Test Plan]
1. Use a Lenovo platform SE30 including 4G Quectel EM160 modem and an AT&T SIM card in US
2. Enable 4G modem and connect to AT&T apn
$ sudo mmcli -i 0 --pin=0000
$ sudo mmcli --modem 0 --enable
$ sudo mmcli -m 0 --simple-
$ sudo nmcli radio wwan on
$ sudo nmcli connection add type gsm ifname wwan0p2MBIM con-name mymodem apn emome
$ sudo nmcli connection up id mymodem
3. Check if the MTU got from the following results are the same:
$ sudo mmcli --bearer 5 | mtu
$ ifconfig mhi_mbim0 | grep mtu
* Expected result:
Both MTUs are the same value 1430
* Actual tested result:
Different values (one is 1430 , another is 1500)
[Where problems could occur]
Very low.
This is a simple fix: network-manager gets the MTU from the ModemManager then sets the MTU of the modem interface.
[Other info]
1. Network-manager v1.30.0-1ubuntu3 in hirsute has included the fix.
Changed in network-manager (Ubuntu): | |
importance: | Undecided → Medium |
Changed in network-manager (Ubuntu Focal): | |
importance: | Undecided → Medium |
Changed in network-manager (Ubuntu): | |
status: | Confirmed → Fix Released |
description: | updated |
The .debdiff file “network- manager_ 1-1.22. 10-1ubuntu2. 3-focal. debdiff” is attached for focal(20.04).