@grandadbaza 

Hi,

I think for the new TL-WPA4221 to automatically join the existing network the new TL-WPA4221 needs to be plugged into a socket that is located very near the socket where the existing TL-WPA4221 is already plugged in.

If you can't get it to join that way, then manually pair the new TL-WPA4221 with the existing one by using the physical "Pair" buttons on each device, like explained in the user manual. (see below)

Thanks for your reply  

I just left it plugged in last night and got up this morning and it has connected , Goes to prove that sometimes doing nothing does things LOL

Another question ist it possible to connect one of my older TL-PA210 adapters to my new system ?

  @grandadbaza

spoke too soon , moved it upstairs where its needed and won't connect ,tried different sockets to no avail

  @grandadbaza

I have tried it in various sockets downstairs and it works fine  but not in any of the upstairs sockets,  Puzzled! the TL-PA210  set-up worked for years 

  @grandadbaza 

I don't know why the TL-PA210 worked upstairs while the TL-WPA4221 does not.

You should be able to pair the old TL-PA210 with the new TL-WPA4221 by following the procedure from the user manual that I posted a few posts back. The key for success is to plug the adapters into sockets that are not to far apart from each other.