An alternative solution (from the Avast website):
"To overcome this vulnerability, aside from applying the firmware update that addresses the issue, there is one more technique that can be used: setting up port forwarding for port 80 on the router to an unused IP address on your network. To do that, enter your router configuration page and find the "Port forwarding" section. Here, set up a rule that tells the router to send all
http traffic to an unused local IP address (for example 192.168.0.255, if this address is not used by any other device on the network)"
https://help.avast.com/en/ws_android/1/alert_vulnerable_router.html#solution
Getting into your router's settings is easy enough. Simply type 192.168.1.1 into your browser's address bar and hit 'Enter'. Unless you or TalkTalk have changed the default settings, enter 'admin' as both the username and password. You'll then need to click on 'Advanced'. After that you'll need to look for the option to forward traffic on Port 80 but googling doesn't make it exactly clear what you'll need to do then.
The issue is further complicated by the fact that there are different TalkTalk routers. However a Youtube search for 'TalkTalk port forwarding' appears to offer instructions which might help.