T-Mobile ONLY Mediatek Cheetah RM520N-GL - IPV6 Fix My WAY

ATTENTION This is not an upgrade

T-MOBILE SPECIFIC IPV6 fixed
NOTE: follow steps in this order, I've tried in different order and failed this is what has worked for me. 

Do not follow this post "if it ain't broke"

Maintenance - Restore System

Unplug power from wall (not from unit) -> replug

STEP 1
Under Network (menu)
IPV6
enable NAT6
and Save
Data will briefly disconnect

STEP 2
Under 5G NetWork
APN - IP Type select IPV6/V4 and Save

Do not change APN leave on Auto

go to 5G info make sure ipv4 and ipv6 addresses are displayed

IPV6 will now be working