Cisco 2901 Router Config -- 3

I have a customer who is having problems with their AT&T dedicated Ethernet circuit. This is not a managed circuit, so AT&T will not touch anything past the demark. AT&T has delivered a 50mb dedicated Ethernet pipe to the building demark, where the speed tests 47/47 at their switch. From that point there is a fiber run that connects the MDF to the 6th FL IDF closet. Fiber connects straight into a media converter. Speed test after the media converter is 47/25. From the media converter a copper cat5e patch cable connects to a Cisco 2901 router. Speed test connected to the cisco router is 15/8. I am not a Cisco expert at all, and need someone who understands the correct config to use where it will not cause such heavy derogation. Anyone who works or used to work for ATT would be preferable in the DC area. I have pics of the current environment if needed. Price can be discussed. Please email me. Sean Binette