Hello Saugata Dutta1,
Thank you for posting in Microsoft Community forum.
1.Based on the description "But people outside the office premise are unable to join the domain or change the domain user password.", are the devices connected to domain network via VPN when people outside the office premise?
2.What error message does the people receive when joining the domain?
3.What error message does the people receive when changing the domain user password? ****Based on my knowledge, joining the domain or changing the domain user password needs to connect to company domain network.
I hope the information above is helpful.
If you have any question or concern, please feel free to let us know.
Best Regards,
Daisy Zhou