It seems the problem was with the phone. There was an android update about the same time when I installed the TP Link router, which somehow turned on the setting to search for Hotspot 2.0 networks on...

Dear all, I have installed WiFi router Archer C1200, which works as expected except for 1 android mobile phone. The beauvoir is quite strange, if you could help me debbug it, that'd be really great....