@Mus3b 

Please provide the information below so that we can do further analysis. 

1. What is the bandwidth you paid for your ISP? And what is the speed you can get from the RE650?

2. What is the current light status of the extender?

3. How far away between the main router and extender? what about the signal strength?

4. With a computer connected to the extender, please check the wired speed and wireless speed separately. Then please show me the pictures of test results.

Meanwhile, please check the wired/wireless link speed: https://www.tp-link.com/support/faq/2265/

5. To do a comparison analysis, please put your computer next to the extender and connect it to the main router to run the speed test and show me the result. 

6. Besides, you can refer to the information below to troubleshoot.
https://www.tp-link.com/support/faq/2232/

Any updates, please let me know.

Thanks a lot.