TP-Link ER605 and Synology 918+: Synology cannot access internet

This has to be the most helpful networking community on the internet - Thank you

I have just installed a TP-Link Omada 605 and now my 918+ NAS cannot see the internet. I have other clients on the same subnet which have no issues and the DHCP configuration to all the other clients are good.

The NAS is set up to recieve a DHCP lease and it does get one, however when I go to assign a manual DNS address ( in the Synology, it fails to set up. This is probably because the router is blocking the synology.

When I SSH into the NAS, I can ping the 605 gateway but not anything outside of the local 10.X.X.X subnet. ICMP service type in Omada is set to ALL. I can ping from the Omada.

I have turned off all the firewall rules in the Omada interface and the 918 still cannot access the WAN.

Does anyone have any clues on how to set up the Omada to allow the NAS access to the WAN.

TLDR: I have just tried a Domestic Asus router and the NAS can go through - so it is something to do with the router setup.

I use Omada but only for an Access Point.

TP-link ripped off unifi, so I’d probably look in eithers forum for a solution, but it sounds like it’s a config error, strange problem to have.

When connected to the Asus with a static IP and then re-connected to the TP-link it still fails?