Can I use a wireless router to connect to mobile buildings?

[Pinkflipflop]

Advice on this woud be fantastic.

If one office has the Internet and access points can I use a wireless router to allow the other office to connect to the Internet?

The offices are about 15 feet apart and are mobiles.

What sort of router woud be best?

If the offices are only 15 feet apart, then yes, I would expect that you could pick up the wireless network in one from the other, unless the walls are really thick stone (not likely in mobile offices I presume). Any wireless router would do it if they're that close.

But I don't think you want to connect with a wireless router, you just want another wireless access point in the second office.

You should only use 1 router on a single network (a router does what the name suggests and "routes" all the network traffic round the network). If you have more than one router, you will confuse the network.

If you already have a router and want to use that hardware to save money, then many routers can be configured in "Bridging Mode" to connect you to another wireless network, but you will likely want to turn off the second router's DHCP service, and assign it a fixed IP address somewhere sensible within the IP address range of the first router.