Only thing I will laugh at you or scold you about is the maximum length of Cat5, 5e, and 6 cable runs is 328 feet (some folks say 330 feet). If you can't make that, figure out a way to add a good switch. But anyway, glad you got it fixed!
I remember looking that up back in the day. But, I decided then to run it a bit longer and see what happens. It seemed to work ok then. But, I'm guessing that exposure to years of storms and sun and being bunched up in a giant ball had an effect.
I have a feeling emby probably wouldn't be deployable on a router as far as being included in the firmware image due to package size. MiniDLNA is one of several now available, but there have been plenty of others over the years. Personally, I don't think I'd use a router as a media server, but that's just me.
That much is true, neither emby or plex is small enough size wise to fit on a router.