First you should check whether the IPs/hosts are used for anything else WO related, so you don't inadvertently block something important.

If the IPs are not used it should be pretty straight forward to block them on the IP/hostname.
If they are used elsewhere you'll need to block the whole URL somehow, but then your router need some form of proxy functionality. If it does, it should be a piece of cake though.

Maybe your router has some form of "parental control" that can be used for this? Depending on what router you have YMMV quite a lot

Luckily I haven't seen ads for ages, I pray it continues so...