Arch Linux

dalu

Member

Registered: 2014-04-16

Posts: 96

How to tune MTU of an Android USB tethered connection?

I have an Android phone (S10+) and am now using it to connect to the internet via USB tethering.

I did have an issue with having a bridge up and the phone not recognizing an USB connection.
When I disabled the bridge and removed the 1 LAN device from it, the enp0s20f0u9 iface immediately showed up, after I switched the connection mode on the phone to USB tethering.
So that problem was solved.

However, now I'm having an issue with some domains not loading properly.
Some resources missing, etc.
archlinux.org and google.com load fine. but I'm having issues with github.com and other sites.

When I use NordVPN to establish a connection, then everything works fine, but some sites blacklist those IP ranges and I have to go through captcha, which is annoying.

So I'd like to just access the internet via the phone's USB tethering connection without issues.

- how do I determine the correct MTU value?
- what else might be the issue?

The default value is 1500, when I set it to 1492, github loads more, but still has issue. Lower values lead to a worse effect.

ip link set enp0s20f0u9 mtu 1492

2.
Also something else, I tried to create a bond with enp0s20f0u9 as a backup, which lead to the machine having a new local IP address assigned and not being able to connect to anything local or remote. Essentially I'd like to use the phone as a fallback, because currently my DSL connection has awful issues, disconnecting every 1-5 minutes.

Last edited by dalu (2024-11-12 15:15:01)

dalu

Member

Registered: 2014-04-16

Posts: 96

Re: How to tune MTU of an Android USB tethered connection?

I don't think it's an archlinux problem per se.
It also happens under Windows.
It might have something to so with either the Samsung S10+ or IPv6.
After much GooglFU there was 1 post that said that the issues are present on sites that have no IPv6 connectivity.
And yes neither github.com nor xdaforums.com have an IPv6 record.

When connecting via NordVPN, IPv6 connectivity is disabled, in Linux the journal gets spammed

Nov 12 20:32:57 dev.local NetworkManager[903]: <warn>  [1731439977.4497] platform-linux: do-add-ip6-address[2: fe80::446f:c3e2:7c3d:9a06]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:32:59 dev.local NetworkManager[903]: <warn>  [1731439979.4518] platform-linux: do-add-ip6-address[2: fe80::7297:762d:da84:2f0]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:01 dev.local NetworkManager[903]: <warn>  [1731439981.4540] platform-linux: do-add-ip6-address[2: fe80::87a3:fb0a:405a:6f82]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:03 dev.local NetworkManager[903]: <warn>  [1731439983.4557] ipv6ll[0d9622ba8658e3f2,ifindex=2]: changed: no IPv6 link local address to retry after Duplicate Address Detection failures (back off)
Nov 12 20:33:13 dev.local NetworkManager[903]: <warn>  [1731439993.4598] platform-linux: do-add-ip6-address[2: fe80::f2df:a1cb:d2f8:58e5]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:13 dev.local NetworkManager[903]: <warn>  [1731439993.4598] l3cfg[2e5a4ee275867f7d,ifindex=2]: unable to configure IPv6 route: type unicast fe80::/64 dev 2 metric 1024 mss 0 rt-src ipv6ll
Nov 12 20:33:15 dev.local NetworkManager[903]: <warn>  [1731439995.4619] platform-linux: do-add-ip6-address[2: fe80::56d4:2af4:8f09:a9b1]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:17 dev.local NetworkManager[903]: <warn>  [1731439997.4641] platform-linux: do-add-ip6-address[2: fe80::fd9f:6de6:bcc5:449a]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:19 dev.local NetworkManager[903]: <warn>  [1731439999.4662] platform-linux: do-add-ip6-address[2: fe80::446f:c3e2:7c3d:9a06]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:21 dev.local NetworkManager[903]: <warn>  [1731440001.4682] platform-linux: do-add-ip6-address[2: fe80::7297:762d:da84:2f0]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:23 dev.local NetworkManager[903]: <warn>  [1731440003.4704] platform-linux: do-add-ip6-address[2: fe80::87a3:fb0a:405a:6f82]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:25 dev.local NetworkManager[903]: <warn>  [1731440005.4722] ipv6ll[0d9622ba8658e3f2,ifindex=2]: changed: no IPv6 link local address to retry after Duplicate Address Detection failures (back off)
Nov 12 20:33:35 dev.local NetworkManager[903]: <warn>  [1731440015.4762] platform-linux: do-add-ip6-address[2: fe80::f2df:a1cb:d2f8:58e5]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:35 dev.local NetworkManager[903]: <warn>  [1731440015.4763] l3cfg[2e5a4ee275867f7d,ifindex=2]: unable to configure IPv6 route: type unicast fe80::/64 dev 2 metric 1024 mss 0 rt-src ipv6ll
Nov 12 20:33:37 dev.local NetworkManager[903]: <warn>  [1731440017.4784] platform-linux: do-add-ip6-address[2: fe80::56d4:2af4:8f09:a9b1]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:39 dev.local NetworkManager[903]: <warn>  [1731440019.4803] platform-linux: do-add-ip6-address[2: fe80::fd9f:6de6:bcc5:449a]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:41 dev.local NetworkManager[903]: <warn>  [1731440021.4827] platform-linux: do-add-ip6-address[2: fe80::446f:c3e2:7c3d:9a06]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:43 dev.local NetworkManager[903]: <warn>  [1731440023.4847] platform-linux: do-add-ip6-address[2: fe80::7297:762d:da84:2f0]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:45 dev.local NetworkManager[903]: <warn>  [1731440025.4863] platform-linux: do-add-ip6-address[2: fe80::87a3:fb0a:405a:6f82]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:47 dev.local NetworkManager[903]: <warn>  [1731440027.4881] ipv6ll[0d9622ba8658e3f2,ifindex=2]: changed: no IPv6 link local address to retry after Duplicate Address Detection failures (back off)
Nov 12 20:33:57 dev.local NetworkManager[903]: <warn>  [1731440037.4897] platform-linux: do-add-ip6-address[2: fe80::f2df:a1cb:d2f8:58e5]: failure 13 (Permission denied - ipv6: IPv6 is disabled on this device)
Nov 12 20:33:57 dev.local NetworkManager[903]: <warn>  [1731440037.4898] l3cfg[2e5a4ee275867f7d,ifindex=2]: unable to configure IPv6 route: type unicast fe80::/64 dev 2 metric 1024 mss 0 rt-src ipv6ll

Maybe that's why it works when connecting via NordVPN.

Also, I have now plugged the phone into the router Fritz Box 7590, and set up the connection to go over the tethered usb.
The same issue is present, not completely loading html and/or resources of certain sites, but in Windows it's even worse (less gets loaded).
Depending on MTU size in Linux there are various degreed of success, but no complete success.
Using O2 Germany as ISP.

Idk if there's another forum better suited for this issue.

Right now the DSL connection works, but who knows for how long.
O2 Germany's support is below terrible, you can't report an issue without some 4 number "password" you apparently set when becoming a customer.
You can't talk to a person and they refuse to accept an incident report via forum post or in a written way.
You have  to talk to some voice recognition service over the phone, which then wants that 4 number password.
But you can't find out that password, it used to be possible previously over SMS,
but now you have to wait for a letter to arrive. I've been waiting for a week now for that letter.
They did everything so they aren't reachable and to make it as hard a possible for the customer to get help.
Telefonica O2 big thumbs down.
Try working with your internet going away every 1-5 minutes for 5 minutes.

-thc

Member

Registered: 2017-03-15

Posts: 685

Re: How to tune MTU of an Android USB tethered connection?

Does your USB tethering en*-device get a globally routable IPv6-address?