With Microsoft shortly ceasing any further security updates to Win7 (which I greatly prefer to Win10, will this affect the protection given to my computers by Avast Premium antivirus?
Sooner or later yes … probably later. They ususally release this info on the blog https://blog.avast.com/
If they do as they did with XP and Vista then it is much later https://blog.avast.com/avast-discontinues-support-for-windows-xp-vista
Other posts relating to this, see this reply I made in another topic:
https://forum.avast.com/index.php?topic=231309.msg1530642#msg1530642
As Win 7 support ends, but computers are still useable.
I have two them which i want to use as local network. Celeron based passive component server and one i7 based power laptop which have some softwares that wont work in Win10.
I tried to block them from ISP router as creating firewall block using those computers MAC address. Both worked, but google cromecast run down. No connection after that.
I tried to remove DNS from Win 7, but server wont show anymore on homegroup.
While i have Avast Premium security and its firewall on all computers. How i make filter that allows local homegroup connections but blocks internet connections? Thank you in advance. 
Hi! No, it doesn’t affect the protection from Avast, it still can be used on Win7.