Enable Jumbo Frames Causes External Hostname Problem

StephenB wrote:

Well, its not a naming issue, since you can reach the webserver and it has the same DDNS name. Are you using https or http to access the NAS? Maybe try both, just to help isolate. One challenge is that just because jumbo frames are enabled doesn't necessarily mean that packets > 1500 bytes are being used. Maybe load up wireshark on the PC and take a trace while you are accessing both the webserver and the NAS. Most routers don't do jumbo frames, and certainly your ISP won't. Using the ddns name means that your traffic will be going through your router.

I've tried both http/https but neither work when the router points to the NAS. Pinging the external hostname with packets larger than 1500 bytes obviously fails since the WAN MTU is 1500...

The NAS and PC are both on a Jumbo frames supported switch and not connected directly to the router. File transfers and shares both work regardless of whether or not jumbo frames is enabled on one or both. If I point the router to a spare PC (with jumbo frames) running a webserver on the same switch, I can use the external hostname without a problem, but that's not the case with the NAS.