Avast doesn’t have a firewall does it?
No, not in the free version. I'm not sure about the full version. But you don't need another firewall. The Windows firewall more than suffices. And if you're behind a router, that router is also a firewall. All another software firewall does is fight with the Windows firewall and cause problems. More often than not, people don't know to disable the Windows firewall if they use a virus software firewall. And if the two are able to coexist, a second firewall is redundant to the Windows firewall and especially in addition to the router firewall. This uses memory and other resources that can be better used with other applications if not just plain keep the computer running at it's peak speed. Norton is the worst about this.