I’ve been using Avast IS for some time now, and I’ve been using native Windows function - hosted network, to share connection across my other devices via WiFi (I have only one modem, plugged in to usb port). Recently (can’t exactly say when) Avast firewall started to block connection. I can still connect to network using other devices, but as long as firewall is turned on on my main pc, there is ‘no internet connection’ on others. When I disable firewall, everything works great. I HAVE intenet sharing mode turned on, I have latest (12.3.2280) version, I’ve restored default settings of whole Avast IS. What can I do to make it work?
Is the firewall set to public or private for that network connection ?
Both (‘outside’ connection with my internet provider and hosted network) are private and Network Sharing Center in Windows shows them both as having internet.
Not possible.
Per network the avast firewall can only be set to one of the options.
What do you mean by ‘one option’? There should be only one network? How is that, when I have two connections, one per ethernet, and one per hosted network via wifi? What’s not possible?
Per network connection the avast firewall can only be set to either private or public.
Ok, and it’s private, what’s not possible?
what's not possible?See reply #1, #2 and #3
Anyway, it doesn’t answer the question. Connections are private, here, I’ve said it again. What’s the solution?
Disable ICS and connect the other devices directly to the modem.
If it is only a modem, replace it with a modem/router combination that supports WiFi.
or
setup the firewall rules correctly.
https://www.avast.com/faq.php?article=AVKB25
I wish I could use a router, that would solve all problems right away, but unfortunately it’s not the option. I can’t also connect other devices directly to modem, 'cause those are phones and kindle, and, as I said, modem is connected through usb standard port.
And I’ve figured it out that something must be changed in firewall settings, but I’ve seen article you’re pointing me to, and it’s not very helpful. Could you be more specific? Which process should I set up and how to make hosted network work?
So you have :
ISP > modem > pc > other devices ?
If that is so, where is the WiFi ?
Are you sure the modem is just a modem and not a modem/router/(firewall) ?
What make/model is it ?
Modem/routers are real cheap.
You can get a second already for about $10/€10
Money is not a thing 
And yes, that route (ISP > modem > pc > other devices) is correct. WiFi is in pc, I share network with Windows built-in function, called hosted network, via WiFi. Well, I used to.
If money is not a issue, get yourself a decent modem/router and setup things properly.
Your setup is really as it was sometimes needed in the stone-age of networking.