Universal Media Server | Forum

UUID is part of the headers that are sent when a device is identifying itself on the network. I'm sure its more than that but thats as much as I know.
However some devices don't use it like the PS4.

Usually the UUID is used when a custom conf is made, if it exists, otherwise it uses the IP.

To find out what a device uses check the [...] button on a renderer and choose info. It should show details about the renderer and includes udn which is the UUID if it has one.

I got no more ideas how to improve it, I know little about networking besides letting everything set up automatically.

The PS4 and UMS speed-tests will probably always be different as the PS4 is directly accessing the internet via the router, but the path to your PC goes from the PS4 to the router then to the PC and that last path will be shared by anything else your computer is doing.

I don't think you will get over 100Mb/s with the PS4, Mine is around 80Mb/s last I checked and I don't use anything besides windows firewall.

I have seen in other's logs where they get less than 20Mb/s on their PS4's and it still works fine for them.
As long as you are not getting very low speeds like you were originally I think you are good.