:: Re: [DNG] IPv6 slow on one of my Li…
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Author: jeremy ardley
To: dng
Subject: Re: [DNG] IPv6 slow on one of my Linux hosts

On 10/11/23 22:20, Michael S. Keller via Dng wrote:
> I did not have the opportunity to use the onboard NIC for this
> point-to-point test, but with the USB network adapter, I saw no
> slowdowns on a point-to-point link, while I did when it was connected
> to my greater home network.
> I saw no sign in syslog of an address conflict.
> On 11/8/23 15:50, jeremy ardley via Dng wrote:
>> On 9/11/23 05:37, Michael S. Keller via Dng wrote:
>>> On 11/8/23 14:51, jeremy ardley via Dng wrote:
>>>> On 9/11/23 03:56, Michael S. Keller via Dng wrote:
>>>>> My oldest Linux host has trouble with IPv6. Apparently it's the
>>>>> only host in my home network that does have trouble with it (of
>>>>> those that can do IPv6), and I've run out of ideas. All tests are
>>>>> in the same network - traffic does not cross into my ISP's area.
>>>>> The same symptom has persisted across two different switch/router
>>>>> combos - first an old Airport Extreme, now a TP-Link Deco XE75.
>>> >Try setting up a direct cable connection between the two devices
>>> >without a switch. That will eliminate the possibility of other
>>> devices >on the LAN causing the problem.
>>> What sort of interference are you positing, that would affect just
>>> this one host, and only with IPv6?
>>> _______________________________________________
>> There are several possibilities, but by just running a cable between
>> devices you can isolate the problem to the specific host/O/S components.
>> Example of interference from other systems could be QOS shaping, IPv6
>> address conflicts, hardware faults, security software. etc etc.
>> If the single cable shows the same faults you can then examine things
>> like MTU, /etc./sysctl.conf, net.ipv6.tcp_rmem, |net.ipv6.tcp_wmem,
>> |and look for differences from other systems without the problem.

I suggest running wireshark on the host with the problem. Even if the
host has no graphics, you can run wireshark and view results via ssh on
a different system.