A gateway solution with TrueNAS scale and Nextcloud

I got my first instance of nextcloud running today, here are the specs
IBM X3550 M3
2x 1 TB WD AV 2,5" drives
1x IBM 10K SAS 146 Gb
2x Xeon E5506
4x 4GB of DDR3 ECC RAM, total of 15,6 GB of which are usable by the TrueNAS scale.
The problem for me, is that since I am selfhosting, what would be the best way to set up a VPN, and port forwarding on my router to the server.
I would like to be able to access those files when on the go, and I have already setted up Secure enough passwords for this.
I was not able get the apt package manager to work on my install, so

this thread did not sadly work.
Any ideas and recommendations?