Just a quick further update on my D6220. Because of the issues I have in this house with wifi I decided to try my powerline kit to get better wifi downstairs. Now I know that there are many here who think these are something which should not exist but anyway I thought OK if it screws up my connection I can remove them. Well my experience with these are quite different from my earlier trial with the ZyXEL routers. My error rate has not significantly changed since I started using them, I am getting the same relatively low FEC rates as before which are significantly lower than the ZyXELs anyway without powerline and virtually zero CRCs and my ES rate is still in single figures per day for D/S, U/S is a little higher but still the same as it was prior to powerline.
Now I have done things slightly differently in that the powerline near the router is not in the same socket as the router and my router and other kit is connected via a surge protector which was not how it was before. Anyway I see no reason now to remove the powerline, of course YMMV.
Stuart