WiFi "Authentication problem"?

At my parents’ place and cannot for the life of me get my T-Mobile One to connect to their router. My Galaxy Nexus and wife’s Galaxy Note 2 connect just fine using same settings, as well as a slew of laptops. My One just spits back an "Authentication problem." Any ideas? Have rebooted the phone and router numerous times, tried forgetting the network, quadruple checked the key.
Sent from my HTC One using Tapatalk 2.
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Any help wll be appreciated.
Thank you