Most TCP connections failing [Solved]

ant77i · 2026-08-05 20:19:01

Hello

Since a couple of days ago most of my connections have been failing. Some sites seem to still be working, like youtube and google, but most other sites dont. I tried the disabling tcp_ecn and the list of sollutions on the Networking wiki page, even the TCP window size thing i know nothing about.

Here are some of my logs
https://paste.c-net.org/McgrawWifey

and the journalctl log
https://paste.c-net.org/RetainHowie

If any more of my logs are needed or there is some information about the system i can give, please let me know.

Thank you in advance

Last edited by ant77i (2026-08-11 10:27:30)

seth · 2026-08-05 20:38:31

You've an IPv4 lease via enp8s0
firewalld is running and there're plenty of errors from bogus rules - what if you disable it?
(A lot of that seems related to docker, so disable dockerd and containerd as well)

Aug 05 22:08:06 galaxyarch NetworkManager[546]: <info>  [1785960486.7340] manager: (30:50:CE:07:DD:D5): new Bluetooth device (/org/freedesktop/NetworkManager/Devices/3)
Aug 05 22:08:06 galaxyarch NetworkManager[546]: <info>  [1785960486.7340] device (30:50:CE:07:DD:D5): state change: unmanaged -> unavailable (reason 'managed', managed-type: 'external')
Aug 05 22:08:06 galaxyarch NetworkManager[546]: <warn>  [1785960486.7341] device (30:50:CE:07:DD:D5): error setting IPv4 forwarding to '0': No such file or directory
Aug 05 22:08:06 galaxyarch NetworkManager[546]: <info>  [1785960486.7343] device (30:50:CE:07:DD:D5): state change: unavailable -> disconnected (reason 'none', managed-type: 'full')
Aug 05 22:08:06 galaxyarch NetworkManager[546]: <info>  [1785960486.7344] policy: auto-activating connection 'Redmi Leo Network' (755b037d-b35f-499e-b8e6-5e26ed977694)
Aug 05 22:08:06 galaxyarch NetworkManager[546]: <info>  [1785960486.7345] device (30:50:CE:07:DD:D5): Activation: starting connection 'Redmi Leo Network' (755b037d-b35f-499e-b8e6-5e26ed977694)
Aug 05 22:08:06 galaxyarch NetworkManager[546]: <info>  [1785960486.7346] device (30:50:CE:07:DD:D5): state change: disconnected -> prepare (reason 'none', managed-type: 'full')
Aug 05 22:08:06 galaxyarch NetworkManager[546]: <info>  [1785960486.7346] manager: NetworkManager state is now CONNECTING
…
Aug 05 22:13:27 galaxyarch NetworkManager[546]: <info>  [1785960807.8032] policy: auto-activating connection 'Redmi Leo Network' (755b037d-b35f-499e-b8e6-5e26ed977694)
Aug 05 22:13:27 galaxyarch NetworkManager[546]: <info>  [1785960807.8034] device (30:50:CE:07:DD:D5): Activation: starting connection 'Redmi Leo Network' (755b037d-b35f-499e-b8e6-5e26ed977694)
Aug 05 22:13:27 galaxyarch NetworkManager[546]: <info>  [1785960807.8034] device (30:50:CE:07:DD:D5): state change: disconnected -> prepare (reason 'none', managed-type: 'full')
Aug 05 22:13:33 galaxyarch bluetoothd[544]: profiles/network/connection.c:connect_cb() connect to 30:50:CE:07:DD:D5: Host is down (112)
Aug 05 22:13:33 galaxyarch NetworkManager[546]: <info>  [1785960813.0381] bluez: NAP [/org/bluez/hci0/dev_30_50_CE_07_DD_D5]: connect failed: GDBus.Error:org.bluez.Error.Failed: Input/output error
Aug 05 22:13:33 galaxyarch NetworkManager[546]: <warn>  [1785960813.0382] device (30:50:CE:07:DD:D5): NAP connect request failed: GDBus.Error:org.bluez.Error.Failed: Input/output error
Aug 05 22:13:33 galaxyarch NetworkManager[546]: <info>  [1785960813.0382] device (30:50:CE:07:DD:D5): state change: prepare -> failed (reason 'bluetooth-failed', managed-type: 'full')
Aug 05 22:13:33 galaxyarch NetworkManager[546]: <warn>  [1785960813.0383] device (30:50:CE:07:DD:D5): Activation: failed for connection 'Redmi Leo Network'
Aug 05 22:13:33 galaxyarch NetworkManager[546]: <info>  [1785960813.0384] device (30:50:CE:07:DD:D5): state change: failed -> disconnected (reason 'none', managed-type: 'full')
Aug 05 22:13:33 galaxyarch NetworkManager[546]: <warn>  [1785960813.0384] device (30:50:CE:07:DD:D5): error setting IPv4 forwarding to '1': Invalid argument

What is that? And why? Looks like some network via BT to your phone?
Disable that as well.

=> network stable again?
Start to re-introduce the parts you removed, starting w/ only firewalld (to figure whether it's that or docker is pulling a fast one on you)

ant77i · 2026-08-07 11:29:56

I disabled firewalld, docker and containerd.

What is that? And why? Looks like some network via BT to your phone?

A long time ago I used my phone to share the network connection through cable or bluetooth, so I also removed that now.

Unfortunately, non of these helped. Heres the link to my new journal log, maybe theres something new there.
https://paste.c-net.org/FlirtingBagels

seth · 2026-08-07 11:38:46

'key, let's then have a look *how* they actually fail

curl -vL 'http://bad_site.com' > /dev/null

ant77i · 2026-08-08 18:38:29

Here's the output:
paste.c-net.org/HamptonRefuse

The request to google goes through, but to archlinux fails and the command hangs at the last line.

seth · 2026-08-08 18:46:53

Ftr, no IPv6 involved.

So there's no server response on the TLS handshake - do you run into this w/ unencrypted connections?
Does it help to lower the MTU?

sudo ip l set enp8s0 mtu 1200

https://wiki.archlinux.org/title/Networ … eue_length

ant77i · 2026-08-11 09:22:51

Wow, lowering the MTU suddenly fixed everything. Thank you so much. I dont use the forum often, do I now set the topis as solved?

seth · 2026-08-11 10:16:04

Mark resolved threads by editing your initial posts subject - so others will know that there's no task left, but maybe a solution to find.
Thanks.

On topic, did you try to use jumbo frames?
1500 is kinda the "industry standard", a hop w/ a smaller unit in the way would cause universal troubles.
Another thing's that VPNs usually introduce some overhead which is why it's the necessary to lower the unit size behind them < 1500, but I don't recall seeing one in your journal

Arch Linux

#1 2026-08-05 20:19:01

Most TCP connections failing [Solved]

#2 2026-08-05 20:38:31

Re: Most TCP connections failing [Solved]

#3 2026-08-07 11:29:56

Re: Most TCP connections failing [Solved]

#4 2026-08-07 11:38:46

Re: Most TCP connections failing [Solved]

#5 2026-08-08 18:38:29

Re: Most TCP connections failing [Solved]

#6 2026-08-08 18:46:53

Re: Most TCP connections failing [Solved]

#7 2026-08-11 09:22:51

Re: Most TCP connections failing [Solved]

#8 2026-08-11 10:16:04

Re: Most TCP connections failing [Solved]

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