Hi guys, this might be a bit specific

Basically, my Ax1800 is connected to a modem by my ISP. The internet in my room was not good enough so I bought an AC750 extender, which was set up properly and works fine. However, I decided to try and enhance my internet more by plugging in an AX1500 into the extender and it worked..for about 30 mins. 

The Internet extender still shows up and i can connect properly, the AX1500 shows up but when I connect, no matter the device, it says "connected without internet". All of the lights on both are glowing and it seems fine, does anyone know what could've caused the change so suddenly? Thanks in advance!