<p></p>
<p dir="auto">Fair enough.  I will do what I can to help, but may not collect the confidence to do this in Kamailio, at least not without backup from a core developer.</p>
<p dir="auto">I have started some tooling to measure these problems, <a href="https://gitlab.com/0cpm/mtugames/-/blob/master/veth/experiment.md" rel="nofollow">available here</a>.</p>
<ul dir="auto">
<li>My observation that <code class="notranslate">veth</code> ethernet pairs (on Linux) could work around the problem is now falsified.</li>
<li>My next hope is to use <code class="notranslate">SO_REUSEADDR</code> or <code class="notranslate">SO_REUSEPORT</code> to open a secondary socket with a lower MTU, and fallback on that for resends.</li>
</ul>
<p dir="auto">I will continue to do these experiments outside of Kamailio, to avoid its complexity.  If this works, it is most likely after integration with immediate resends.</p>

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