Open Media Vault behind a NAT router

more info is needed, I can access to my OMV from outside my home without problem.

my steps:
1. create a ddns acount and configure properly to point to your external IP
2 Configure router NAT to redirect all incoming conetion from port 80 (better 443 to use Https) to you local IP (eg: 192.168.1.x)

and thats all, then you can acces to your NAS from office , symply need to know your URL, like https://myconfiguredddns.net/