Hello   @amador 

Thank you for creating a detailed post and share the photo.

From the photo the Powerline rate between TL-PA7010 kit is pretty slow, only  148 Mbps. That could mean the distance is too far or your house powerline evironment is not very ideal or suitable for the powerline devices.  Here is an article explaining the powerline rate ( speed on tpPLC Utility/ app) and the actual speed test result: 

Explanation about the Powerline Rate and Actual speed of the Powerline Adapters

You could try some suggestions here and see the power line rate can be higher. 

• Remove the factors that could affect the powerline rate as guide below

What can I do if my powerline rate is very low?

• Try a different Wall socket for the Main/ Extender powerline unit and see if they could get higher link speed 
• Try a different Ethernet cable between router and main adapter or check router port and see if Port Speed is 1000Mbps, not 100Mbps