OK, I have had this problem before.
I don't remember whether they just decided to see other again or the fact that I re-started one or the other, because in the past, one can see the other but not vice-versa.
This time, they both cannot see each other and it's been like this for 3-4 weeks. I have restarted both (within 24 hours of each other) but still no recognition on either.
Both are using an ethernet cable plugged into powerline box.
Both connect faithfully to get the EPG everyday and on demand.
I know this has been reported before, but I haven't seen a solution.