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LTE interface dosen't come up
Closed, ResolvedPublicBUG


This issue found and initially submitted in VyOs forum very detailed and link is given below.

When we configure LTE (ppp) interface wlmX, and try to bring up the interface doesn't come up. The root cause is the PPP commands script generation by the CLI frame for wlmX interface has a bug.

This is fixed and generating this bug to submit the fix.


Difficulty level
Normal (likely a few hours)
Why the issue appeared?
Will be filled on close
Is it a breaking change?
Unspecified (possibly destroys the router)

Event Timeline

SubramoniaPillai changed Version from All to heilum.Jun 20 2018, 5:01 AM
shayyaps added a subscriber: shayyaps.EditedJun 20 2018, 5:11 AM

I could see that T656 was already created, as a result of

However, T656 also wanted to fix a few other items. Perhaps, we can just fix the interface naming issue alone as part of this issue, and use T656 for other issues. The fix proposed by Subbu will make pppd to create the interface with wlm0 in the very first attempt, rather than the existing model of having pppd create the interface as ppp0 and then use the 0003_rename-wirelessmodem to change the name, thereby leaving pppd in an inconsistent state

nuviso@ubuntu:~/vyos/build-iso/pkgs/vyatta-wirelessmodem$ cat 0001-T701-LTE-interface-dosen-t-come-up.patch
From 00a04474535ec0eb2b17fe1d4368abff7f3aae46 Mon Sep 17 00:00:00 2001
From: Subramonia Pillai <>
Date: Wed, 20 Jun 2018 10:57:53 +0530
Subject: [PATCH] T701: LTE interface dosen't come up

templates-cfg/interfaces/wirelessmodem/node.def | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/templates-cfg/interfaces/wirelessmodem/node.def b/templates-cfg/interfaces/wirelessmodem/node.def
index 69d44fc..f185b93 100644

  • a/templates-cfg/interfaces/wirelessmodem/node.def

+++ b/templates-cfg/interfaces/wirelessmodem/node.def
@@ -60,7 +60,7 @@ end: if [ -f /var/run/ppp-$VAR(@).pid ]; then

echo -e "lcp-echo-failure 0\n115200" >> $tmpfile;
echo -e "debug\nnodefaultroute\nipcp-max-failure 4" >> $tmpfile;
echo -e "ipcp-accept-local\nipcp-accept-remote\nnoauth\ncrtscts" >> $tmpfile;
  • echo -e "lock\npersist\nlinkname $linkname" >> $tmpfile;

+ echo -e "lock\npersist\nlinkname $linkname\nifname $linkname" >> $tmpfile;

if [ -n "$VAR(./network/@)" ]; then


This comment was removed by SubramoniaPillai.
syncer triaged this task as Normal priority.Jun 20 2018, 3:09 PM
syncer removed projects: VyOS 2.0.x, VyOS 1.1.x.
pasik added a subscriber: pasik.Mar 12 2019, 6:13 PM
c-po added a subscriber: c-po.May 4 2020, 3:00 PM

Forum says issue is fixed. Also WWAN underwent a major rewrite - should be all good now.

c-po closed this task as Resolved.May 4 2020, 3:00 PM
c-po set Is it a breaking change? to Unspecified (possibly destroys the router).
c-po moved this task from Need Triage to Finished on the VyOS 1.3 Equuleus board.May 21 2020, 5:25 PM