@MP2021  Hello, 

Here is similar thread and that customer found its router's LAN port issue,you could also start troubleshooting from router and here are some suggestions: 

1. Please connect a computer to router's LAN port and make sure computer could get Internet from router via Ethernet 

2. Remove other devices connect to router's LAN port and try a different LAN port on router

3. Change a different Ethernet cable between router and the adapter 

4. Try to eliminate the possible factors that affect the power line environment with the instruction below：

https://www.tp-link.com/support/faq/409/

5. Double Examine your network topology:

Router -<Ethernet cable>-- wired powerline unit   ________ powerline ______ wireless powerline 

If possible, you could test the power line KIT with a different router

If still the same problem, may I have a photo of the label of Media Hub showing its Model, and your network topology? Do you use a VDSL line? Thank you