Infected Router

Big problem - infected router

I have W7. Avast found 5 routers on my system I didn't know anything about. I didn't even know I HAD one. Maybe the guy who owned my PC before me did it. I thought routers were external devices. One on the list was for, or from, Android. I don't have anything but a desktop PC. I have a modem from my provider - is THAT a router?

Avast told me my router is infected, but not which one. I don't want more than one, or ANY, without a good reason.

I was given a lot of information about what happens when my router is infected, but not how to stop it.

At least one of these 5 routers looks very suspicious. The first digits of the DNS in the other four routers reflect my IP address with variations.

How can I get rid of it? It may explain why my memory drops to 3% or less so often in the last two years.

It calls itself: IP fe80.0000.0000.0000.04c9.268b.2a24.64d0

I can't read the name of it - the text is too small and faint for me to read.

As usual, the pitiful W7 Search is useless. It can't find the word router.

When I investigated, I had so many open windows I couldn't keep track - none of them gave me info I could use, but I did get warnings that device failures could happen if I didn't do it right.

Can someone help walk me through this? I'm way out of my depth.
Holly B.