@BertB I think Question 2 on the FAQ probably answers my query https://www.tp-link.com/uk/support/faq/1794/ I guess I'll purchase and find out for sure.

@cacb Thanks for the reply with the details of a similar setup. The problem I have is the building with the router is at the end of the garden it and the main house are stone built so very little...

Prior to purchase I'm wondering if anyone can confirm if my intended network will be OK. The main M9 unit will be connected to the isp router (bridge mode on router). There is then a 20m ethernet run...