Mac Pro; TP-Link Router & NAS Issues

Hi,

I've searched the internet high and low and been unable to find anyone else who has experienced this issue.

If you have any advice or guidance, it will be gratefully received.

I have a Mac Pro connected to a TP Link Archer D7 router via an ethernet cable. The router is connected to a BT modem and a NAS box via ethernet (Synology 415 Play).

Since I replaced the router over the weekend, connecting to the NAS directly has become impossible. The Mac hangs and then crashes without fail. This is incredibly frustrating as my NAS stores all my pics, videos and music not to mention a Time Machine back up. Before I upgraded the router, the NAS and Mac were connected to a BT Business Hub which worked a treat.

I can't connect to my NAS via OS X or via a browser. However, if I connect to my NAS going outside the LAN using DDNS amazingly it does connect. The same thing happens when I connect wirelessly. Everything works normally when connected wirelessly, however given the distance between the Mac Pro and router it's incredibly slow.

I've pinged the IP and it works fine. I can see in OS X that the disk is there on the network and ready to be used, I just can't get onto it.

According to a lengthy spell with Synology support, it's to do with the router and Mac connection.

Have you experienced this issue and if so, did you solve it? Are you aware of anything that would cause the computer to hang when trying to connect to it?

Any help or guidance will be gratefully received.

Sincerely,

Tarmak