Crashing on WIFI sync

My Fenix has been syncing no problem via wifi since I bought it. However today it developed a problem.

First issue was I tried to sync via wifi and it gave me an error saying that wifi was not available. I knew that my wifi network was working so I restarted my watch. I tried the wifi sync again and instead of giving me an error message it seems to search for wifi, connect, start to sync and then crash. I get the Garmin triangle before it restarts.

I've tried a sync via data cable and that works fine.

Any idea what's causing this? More importantly, any ideas of a fix?

Cheers