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    <p>try lowering your mtu to 1,200 from 1,500 to see if it helps</p>
    <div class="moz-cite-prefix">On 2025-11-20 8:42 p.m., Khalid
      Baheyeldin wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CA+TuoW0rhkE+kesF12470gh47_pvmcL47YKuAb2pikCPR2cjiQ@mail.gmail.com">
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        <div>
          <div style="font-size:small" class="gmail_default">I am having
            a puzzling issue with my VPN network, which uses Wireguard,
            and has been working well for months. </div>
          <div style="font-size:small" class="gmail_default">Then a few
            days ago, things started going wrong.</div>
          <div style="font-size:small" class="gmail_default"><br>
          </div>
          <div style="font-size:small" class="gmail_default">A service
            (e.g. Home Assistant, Grafana) would load from my phone, but
            fails to load from my laptop.</div>
          <div style="font-size:small" class="gmail_default">My phone
            and my laptop are peers in the Wireguard VPN.</div>
          <div style="font-size:small" class="gmail_default"><br>
          </div>
          <div style="font-size:small" class="gmail_default">The issue
            does not seem to be a firewall issue, because I have not
            changed that at all, and I do see responses, but no traffic.</div>
          <div style="font-size:small" class="gmail_default"><br>
          </div>
          <div style="font-size:small" class="gmail_default">When I use
            curl, I get back a response, which is an HTTP redirect:</div>
          <div style="font-size:small" class="gmail_default"><br>
          </div>
          <div style="font-size:small" class="gmail_default"><span
              style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">$ curl <a
                  href="http://s1.example.com:3000"
                  moz-do-not-send="true">s1.example.com:3000</a>
              </span><br>
              &lt;a href="/login"&gt;Found&lt;/a&gt;. <br>
            </span></div>
          <div style="font-size:small" class="gmail_default"><span
              style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"><br>
              </span></span></div>
          <div style="font-size:small" class="gmail_default">
            <div style="font-size:small" class="gmail_default">But when
              I go to that URL, the browser (or curl) hangs there
              indefinitely.</div>
            <div style="font-size:small" class="gmail_default"><br>
            </div>
            <div style="font-size:small" class="gmail_default"><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">$ curl </span></span><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"><a
                    href="http://s1.example.com" moz-do-not-send="true">s1.example.com</a></span></span><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">:3000/login #
                  Grafana, Hangs</span><br>
              </span><br>
            </div>
            <div style="font-size:small" class="gmail_default"><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">$ curl </span></span><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"><a
                    href="http://s1.example.com" moz-do-not-send="true">s1.example.com</a></span></span><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">:8123/ # Home
                  Assistant, Hangs </span></span></div>
            <div style="font-size:small" class="gmail_default"><br>
            </div>
            <div style="font-size:small" class="gmail_default">
              <div style="font-size:small" class="gmail_default">Again,
                some requests with errors do send back responses:</div>
              <br>
            </div>
            <div style="font-size:small" class="gmail_default"><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">$ curl </span></span><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"><a
                    href="http://s1.example.com" moz-do-not-send="true">s1.example.com</a></span></span><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">:8123/foo #
                  Home Assistant, with an invalid URL</span><br>
              </span></div>
            <div style="font-size:small" class="gmail_default"><span
                style="font-family:monospace">404: Not Found</span></div>
            <br>
            <div style="font-size:small" class="gmail_default">But I do
              see bytes being queued in netstat on the target machine
              (3rd column).</div>
            <div style="font-size:small" class="gmail_default"><br>
            </div>
            <div style="font-size:small" class="gmail_default"><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">tcp 0 5606 <a
                    href="http://10.10.0.4:8123" moz-do-not-send="true">10.10.0.4:8123</a>
                  <a href="http://10.10.0.2:50322"
                    moz-do-not-send="true">10.10.0.2:50322</a>
                  ESTABLISHED 4071/python3</span><br>
              </span><br>
            </div>
            <div style="font-size:small" class="gmail_default">Then it
              goes from ESTABLISHED to CLOSING to CLOSE_WAIT ...etc.</div>
            <div style="font-size:small" class="gmail_default"><br>
            </div>
            <div style="font-size:small" class="gmail_default">I
              restarted the Wireguard tunnels on both machines, just in
              case:</div>
            <div style="font-size:small" class="gmail_default"><br>
            </div>
            <div style="font-size:small" class="gmail_default"><span
                style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">$ sudo
                  systemctl status wg-quick@wg0</span><br>
              </span><br>
            </div>
            <div style="font-size:small" class="gmail_default">And it
              made no difference.</div>
            <div style="font-size:small" class="gmail_default"><br>
            </div>
            <div style="font-size:small" class="gmail_default">This is
              happening for various services, but only from specific
              machines, but not others.</div>
            <div style="font-size:small" class="gmail_default"><br>
            </div>
            How can one go about troubleshooting this pesky problem?</div>
        </div>
        <span class="gmail_signature_prefix">-- </span><br>
        <div dir="ltr" class="gmail_signature"
          data-smartmail="gmail_signature">Khalid M. Baheyeldin</div>
      </div>
      <br>
      <fieldset class="moz-mime-attachment-header"></fieldset>
      <pre wrap="" class="moz-quote-pre">_______________________________________________
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