Hello! Thanks for your reply! I never thought that this post get posted. I got great help from the support. But the solution was to upgrade the firmware in the extender. After that...tada! Works...

Model : Hardware Version : Firmware Version : ISP : I got a Netgear Extender WN3000RP that works fine with my old router from Technicolor. Recently I bought a TP-LINK Archer C9 and replaced my old...