This is the situation I've inherited: There are two routers, one off-site. Both are connected to the ISP. The ISP assigns both of them the same static IP (or so it seems). Presumably, the network problems we're having are related to the idea that you can't have two instances of the same IP.
So we rang up the folk off-site and told them to turn off the router. Now everything's working okay here.
How do I get around this? Get another static IP? Figure out how to get the router to ask for a dynamic IP (as we're not using the static IP for anything)?