I purchase a 100 mb download 5mb upload service and I'm not getting the full bandwidth out of the router. I checked the bandwidth directly connecting laptop to modem and I'm getting what I purchase every time I go through the router it drops drastically I'm only getting 20 download and 5 upload. Can someone please explain why this is happening I tried two different routers RB2011UiAS-2HnD-IN and RB3011UIAS-RM.

Bad configuration definitely. Those routers are really capable to provide much bigger speeds when correctly set.

Most likely Ethernet duplex mismatch
Play around with Ethernet speed and duplex settings

thanks for quick reply