@Byelobog 

Good day,

Please refer to the following suggestion to have a look:

1. if possible, please temporarily unplug all the old 4010 adapters, and only plug the new 4220kit, no need to connect the 4010 to the router, just leave them in stand-alone mode;

2. try to pair the two new adapters to see whether they could be paired;

Thank you very much and wait for your reply.

@Byelobog 

Hi，

Did you reset the 4220 by holding the reset pinhole for 10s?

--if still nothing happened, I am afraid that there might be something wrong with it and it needs to be replaced.

Or there are some other suggestions and might be a little complicated:

1. download the powerline utility:

tpPLC_Utility_Windows.

https://static.tp-link.com/2020/202011/20201127/tpPLC%20Utility.zip

2. add the adapter via powerline key:

https://www.tp-link.com/en/support/faq/1615/

and another way—changing the powerline network name:

1. change the powerline name for the 5*TL-PA4010 to be TPLINK for example;

2. plug the computer via Ethernet cable to the 4220 and change its network name to be TPLINK as well;

https://www.tp-link.com/en/support/faq/1616/

thank you very much and wait for your reply.