Question about Wireguard server

[Bruno Wolff III]

On Thu, Jan 04, 2018 at 16:51:19 -0500,
  Stoyan Mihov <t0ny0 at atlantabg.com> wrote:
>Greetings dear wireguards!
>
>I am running wireguard on ubuntu 16.04 server and LEDE on router. When I
>have everything set up on the router - I decided to upgrade to a newer
>version of LEDE. So I did, and then my router would not connect to the
>server anymore (although settings have been saved) until I issue a command
>on the server:
>wg-quick down wg0 && wg-quick up wg0
>
>Then the router automatically connects without an issue. Before that - the
>server would not accept a connection from the router, there are no dmesg
>errors, no errors whatsoever on both sides. It simply doesn't show a
>handshake on the server, and the router sends packets, but receives 0
>packets.
>
>Is there an easier way to fix that issue, so a restart on the server would
>not be necessary every time an upgrade on the router is made? Or am I
>missing something obvious (quite possible lol) that resolves that issue?

Is there NAT involved? I saw similar behavior when a port got moved 
because of a source NAT conflict.