@phaedrux Thanks for your help!
Seems that it was actually just a coincidence that the update and WiFi issue coincided:
Running M997 S1 didn't resolve the issue however I did some further investigation and noticed that ALL of my 2.4 GHz devices were disconnected from my router. After updating my router's channel settings manually and rebooting the router everything is working again, including the Duet2WiFi!
My apologies for the false alarm!