You can search for any of these:
Sygate - has a pro and free version
Zone Alarm - pro & free
Outpost - pro & free
Look n Stop - pro & free
Kerio - pro & free

I’ve never tried Look n Stop along side of avast but all the others have worked for me during testing. If you’re looking for a free fw, I think Sygate is the best overall, but any of these will get the job done.
Hopefully this gets you started.