Last night - long story - my son and I went out.  He has a TP-Link AV600 Powerline to enhance his gaming, first unit is connected downstairs at router, 2nd unit is upstairs from power socket to his PC.

Anyway, I unplugged the downstairs Powerline from router and we took it with us.  So downstairs setup remained of fibre to modem to router.  My flatmate and I pick up internet wirelessly from router.

When we got home, my flatmate said he lost internet soon after we left.  My son has said something similar happens at his mothers if this occurs as well.

Doesn't make sense to us as to why this happens.  Modem connects to router.  Flatmate connects to wireless signal.  When we attach the AV600, it connects router to power point, then in his room 2nd unit connects from power point to his PC.  So, we would have thought the Powerline as connected purely and simply connects his PC directly to router via power lines, and not wireless - so why is other wireless in house affected?

thanks