After suffering thru 1 month of dropped connections (usually 4-6 hrs) using a DIR-655 & DWA-552 NIC I finally have a solid connection. I tried everything suggested in various threads such as QoS disabled, DNS Relay disabled etc. The only change that worked was disable Auto Channel and force to Channel 1. I'm sure other channels would also work but I selected Channel 1 and it's been 4 days and not 1 drop. I was at the point of returning what is otherwise and great router and it's now solid and working as advertised.
John