Hi,  I have set up my AC1750 (RE450) wifi extender unit and the wifi network shows the 2.4 and 5 Ghz Extended network access points on PC but when I go to connect to the extended connections, (system - Laptop Lenovo T480s using Microsoft Windows 10) it requests the 8 digit PIN number or Security Key from my main router. When entered, the system states " Cannot retrieve info from router OR Cannot access Microsoft system" - eh? Nowhere is this mentioned in the set up procedures and the TP linkrepeater.net web site set up is telling I am connected and TP-link connected. No logic to this set up. Anyone had the same issues. Cheers.