I'd like to know what might be causing the repeater to have such slow internet compared to the router's.

I placed it in an area where the router's signal is strong, but the download speed is much lower on the repeater (less than 1 mbps). The router's internet speed drops to about 6 mbps.

Furthermore, when I use an internet speedometer while connected to the repeater's internet, the speedometer simply doesn't start.

I checked these speeds when downloading files.

It's a TL-WA850RE 300mbps White repeater. The router's internet speedometer shows about 40 mbps.