NAT Loopback : Low bandwidth

I would like to confirm that the slow down happens when accessing the server from the LAN side, correct? => Yes, when the client uses the domain name. This means traffic will go to the WAN and the router is supposed to find out that the WAN IP is its own WAN IP and then route back to the server LAN IP address following port forwarding rules. If someone from outside your network tried accessing the server, will you experience the same? => the same client connects from the WAN too and gets the same kind of transfer speed as when it is using the domain name to reach the server from the LAN And when you say bandwidth very low, is this the Internet access? Or it is something else? => About the same as the uplink bandwidth Is the slow down happening on the wireless or it doesn't matter? => Occurs with both Ethernet and Wireless Did you check all your DNS settings on the server side? => Yes By the way, what kind of server do you have? => Synology running DSM 5.1. Clients are using Cloud Station (similar to drop box) or, for mobile devices DS Cloud and DS File.