Thanks for your reply.

Yes I posted that other case too.

I have also posted on the support ticket that I created with the original issue when receiving mail. I am waiting for a reply there. Ticket is #ROF-612-67278 . To make story short: we purchased Avast Premier license for the 3 computers, wanted to have more protection, but had to get a refund due to being unable to receive email on the Windows XP and Windows 7 ones. The Windows 10 one worked well with Premier, it did not cause the problem with the router (my son doesn’t use email programs so I don’t know if there was issue with that on this computer). When we got the Premier cancelled because we could not use it in 2 of 3 computers, we uninstalled it from all (full uninstall) and then installed Free. This solved the issue reported on the other ticket that you mentioned, when receiving email, it works well with Free. But the Windows 10 one has this issue of breaking up the internet connection. Looks like one solution is not good for all.

I can’t try another router, this is the one provided by my ADSL provider.