My second Router the Ethernet is capped at 100mbps HELPPPP

hello, i have been looking for weeks now to try and fix this? no luck? i see people saying it may be bad wires but mine are all cat 6 i had all mine done off the same reel of wire too, now the one going from my virgin media hub into my second router, when i put that into my xbox upstairs or my laptop direct i get 257mbps thats how i know its not bad wiring. when i connect it into my new router as a access point and use that as a wireless point and to branch mulitpul Ethernets into my bedroom it then everything coming out of my second router get capped at 100mbps i dont think my lan ports are capped because it gives me a option of 1gbps any ideas? il post a photo too of what im looking at:

We don't know the make and model of the routers, so hard to give any kind of valid advice right from the start.

sorry here is a picture of the Router Details

If you go here to see the specs for your router:

RT-AC51U | Networking | ASUS United Kingdom

You will notice that the 4 ports are only 10/100 base T and not 10/100/1000. That would explain the 100mb only.

ahh so that ports will only give out 100mbps i see, my internet is capable of 250mbps at least thats what i get downstairs, can you anyone advise me on a good router to buy that will have good enough ports to transfer my internet speed? i mainly use it for gaming thank you for the help btw :)