@Solla-topee Yes, router works fine, all mobile phones are connected to 5GHz. I may have been unclear, but PC(with the adapter) is connected to 5GHz network to, but only when adapter is plugged in...

I Have bought TP-Link Archer T4U V3 half a month ago, downloaded and installed drivers from website(not from CD) and everything worked great, until power outage last night. Today 5GHz network started...