alt Hacker News+1 on AirVPN. They are amongst the handful of companies which successfully resisted the war on torrenting (targeting VPNs that allowed persistent ports) and still allow for port reservation.
Mullvad, like most other VPNs gave in in the end and removed port reservations.
I wonder how AirVPN doesn't run out of ports since you reserve a static port number across all nodes (which is also a fingerprint). They seem to be almost all allocated. Do they just plan to never have more than 64512 customers?