Are you having any other issues with your computers being blocked or is it just that when you check the IP that it shows on the blacklist?
Ok. When I had you perform a hard reset on your router, did you happen to change the password or did you keep the factory default password? Personally I would change it.
I do know the router has a built-in firewall and it's on, that's all.
For security purposes, passwords really should be changed frequently. It can be convenient to have the same password for everything and never change it, though it is not a good idea. Especially if you are experiencing issue with your ISP as you are. If you fear that you may forget your passwords, there are password managing apps that can be used and many of them are free. See here. I am old school so I keep my passwords and all login information for my many sites (including banking) written down in a notebook so I don't forget them and I do change them about once a month.
The 2 computers we checked so far are clean though we do need to remove the tools from the second yet. If you would feel more at peace, we could run scans on that 3rd computer to verify it is clean. Let me know what you would like to do.