Wireless printer suddenly won't print unless firewall is turned off?

So…just happened this week, no updates that I’m aware of…

…wireless Canon Pixma MG6620 multifunction printer suddenly started showing as offline, and won’t print, unless I turn off Avast firewall…

…Canon had me run through a crapton of troubleshooting to see why it stopped, and lo and behold, soon as I disable firewall for 10 minutes, I can print…

I used to see a place in Avast settings for exclusions…but the exclusions thing there now is so abstruse I cannot figure out how to add my wireless printer to it…and what’s infuriating is, I hadn’t needed to until this last week!

Anyone have any helpful tips/instructions for me?

Disable port scanning in the firewall.

Avast UI → Protection → Firewall → Settings → Advanced → Uncheck “Enable automatic port scan detection”