bandwidth with and without router.

I have just upgraded to Ultimate and after a visit from a tech guy who replaced some cable that squirrels had damaged works fine, with one computer. I need to hook up three and I would like them to all be wired connections. I bought a TPLink TL-R600VPN router. It seems that the router drops the bandwidth by a very large % (60-80) Today I tried again to make it work but when I put the router in the system my download bandwidth dropped from around 200 to around 20 but upload is no change at 25-30, this time when I took the router out of the system and rebooted everything my download bandwidth did not come back and is now at 25-30. My Modem is Arris SB8200.

I need to know if a different brand/model of router will solve the problem and if so which one. I am very pleased with the Ultimate program but need to have three computers online with fast bandwidth tests when others are idle.

Thanks in advance,

Nikita