IPV6 on T-Mobile TM-AC1900 router connected to Arcadyan KVD21 Gateway

I have a T-Mobile TM-AC1900 router connected in “Wireless Router Mode” and can not figure how to get IPV6 working on it. Does anyone know if I set it to “Access Point Mode” if it will automatically connect to IPV6? I’m a bit gun shy of trying it because the last time I set it to AP mode I lost my entire Wireless configuration.