title: iOS error: [tcp] nw_proto_tcp_route_init [C1.1:1] no mtu received
body: <p>I have simple iOS App using <code>Network.Framework</code>, <code>NWConnection</code> and <code>NWEndpoint</code> to setup a TCP connection to a Microchip RN-171. It all worked fine until iOS 14 when I started to occasionally get this error:</p>
  <pre><code>[tcp] nw_proto_tcp_route_init [C1.1:1] no mtu received
  </code></pre>
  <p>at which point the connection just locks up with no further data flow in either direction is possible with respect to iOS.</p>
  <p>I'm not well schooled in the art of Network protocols. However looking at the RN-171 data sheet I see that the default value for <code>mtu</code> is 1524 so I am assuming that during the negotiation between the RN-171 and iOS this value should be set and something in iOS 14 means that this value doesn't always get to iOS.</p>
  <p>Any ideas what the root cause might be and how to fix it?</p>