Question : Cisco 1841 router with T1, communication with server very slow…?
I have a cisco 1841 router. The server sits in another building connected with a T1 line leased from AT&T.

Communication with the server is very slow and not stable. A software execution which requires back and forth communication with the server usually takes minutes. Also, big files (>20M) sending to or from the server often get dropped.

I checked the router configuration and don’t find anything suspisious. Don’t know if it is the router or the T1 or the server config that causes this problem.

Anyone has any idea? Thanks!
cisco 1841

Best answer:

Answer by sgtjnlawrence
I doubt it’s your T1. Make sure your NIC card in the server has the proper duplex settings (Best to set Auto) and then make sure that the port on the switch it is plugged into has the duplex setting at the highest speed the server and switch can communicate to. If you have Auto Auto set, you can get a mismatch error which can cause CRC errors and possible slowness.