GL-X3000 Spitz AX "skb_tailroom small" and unstable connection

Technical Support for Routers
1

Hey folks,

I’ve been experiencing intermittent instability with my modem’s connection. It mostly works well but UL/DL speed sometimes gets really slow.

Upon reviewing the log files, the sole warning or error is related to “skb_tailroom small” as follows:

Tue May  7 12:18:10 2024 kern.debug kernel: [29864.374930] skb_tailroom small!
Tue May  7 12:18:11 2024 kern.debug kernel: [29865.139792] skb_tailroom small!
Tue May  7 12:27:48 2024 kern.debug kernel: [30442.538529] skb_tailroom small!
Tue May  7 12:30:01 2024 kern.debug kernel: [30575.050181] skb_tailroom small!
Tue May  7 12:30:57 2024 kern.debug kernel: [30630.909094] skb_tailroom small!
Tue May  7 12:30:58 2024 kern.debug kernel: [30632.278750] skb_tailroom small!
Tue May  7 12:30:58 2024 kern.debug kernel: [30632.374891] skb_tailroom small!
Tue May  7 12:30:58 2024 kern.debug kernel: [30632.733380] skb_tailroom small!
Tue May  7 12:30:59 2024 kern.debug kernel: [30633.688232] skb_tailroom small!
Tue May  7 12:31:00 2024 kern.debug kernel: [30633.798651] skb_tailroom small!
Tue May  7 12:31:00 2024 kern.debug kernel: [30634.603765] skb_tailroom small!
Tue May  7 12:31:01 2024 kern.debug kernel: [30635.373937] skb_tailroom small!
Tue May  7 12:31:01 2024 kern.debug kernel: [30635.524287] skb_tailroom small!
Tue May  7 12:31:05 2024 kern.debug kernel: [30639.157152] skb_tailroom small!
Tue May  7 12:31:05 2024 kern.debug kernel: [30639.339020] skb_tailroom small!
Tue May  7 12:31:07 2024 kern.debug kernel: [30641.468769] skb_tailroom small!
Tue May  7 12:31:08 2024 kern.debug kernel: [30642.718064] skb_tailroom small!
Tue May  7 12:31:09 2024 kern.debug kernel: [30642.880683] skb_tailroom small!
Tue May  7 12:37:05 2024 kern.debug kernel: [30999.052155] skb_tailroom small!
Tue May  7 12:38:06 2024 kern.debug kernel: [31059.654468] skb_tailroom small!
Tue May  7 12:42:54 2024 kern.debug kernel: [31348.414517] skb_tailroom small!

Any idea what these logs mean? Here is the summary of my setup:

  • Using T-mobile 5G SA with band lock (N41)
  • Router firmware: 4.0 (2024-04-19)
  • Modem firmware: RM520NGLAAR03A03M4G_01.201.01.201
  • Using WireGuard client with VPN Policy Base on the Target Domain or IP
  • Using IGMPv3
2

Welcome to the forum. I cannot help you much here, but I will be following. I run into times (not lately - knocking on wood) with dropped packets over wireguard using TMHI on my X3000. I am not sure if I have seen those messages, so I will look and follow up if I have, but it has been pretty solid for nearly 9 days now. I am not touching it until it starts messing up again :). I was getting full speed and no dropped packets straight to the internet though (I am running split tunnel right now while RV is stored, I switch to everything tunneled when camping).

3

@Stereo1324 should i buy GL-X3000 Spitz? is this provide stable internet for 24x7?

4

I'm not sure if my connection is unstable but i'm seeing the same message in kernel and system logs. I'm not running Wireguard. Have same firmware, T-mobile,same band locking on NR5G SA 41. I have no clue what it is but I'm following this to learn.

5

Was there any conclusion to this? I see this message in my logs, but not at the frequency of the original poster thankfully. There seems to be no pattern to it though.

Chris

6

Try changing mtu? 1420

7

On which interface?

root@GL-X3000:~# ip addr | grep mtu
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group defaul t qlen 1000
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel master br-l an state DOWN group default qlen 1000
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br-lan state UP group default qlen 1000
4: ra0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br-lan state UNKNOWN group default qlen 1000
5: rmnet_mhi0: <NOARP,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group defaul t qlen 1000
6: br-lan: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP gro up default qlen 1000
7: ra1: <BROADCAST,MULTICAST> mtu 1500 qdisc fq_codel state DOWN group default q len 1000
8: rax0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br-lan state UNKNOWN group default qlen 1000
9: rax1: <BROADCAST,MULTICAST> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
10: apcli0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default q len 1000
11: apclix0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000

8

modem
Don't you use a modem to access the Internet?

9

Yes, I'm using the modem....is it not one of the interfaces listed? If not, how do I find the MTU it uses? I know how to change it, but not how to find what it is currently if it is not listed in the output of ip addr or ifconfig.

10

It's probably the one named rmnet_mhi0. You can confirm by going to the Advanced Settings (${routerIP}/cgi-bin/luci/) and looking under Network -> IPv4 Upstream -> Device

11

Any solution to this? I am also sering these messages but not as frequent.

12

image
image910×594 25.7 KB

try update this?

13

I have tried setting it lower, but the modem seems to lose this setting after every reboot. Any way to save SIM settings permanently?

14

You can save the settings to a profile.

15

Does apn change?

16

I have tried saving to a profile, but it does not load the profile on reboot and instead loads some sort of "default" autoconfig instead.

17

hello
Can I see it remotely?

18

After performing another factory reset I was able to save settings properly. So far set the MTU to 1420 and have not experienced this error.

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