is it possible to host a hfs server with an ipv6 public ip adress...
Yes, it's possible (IPv6 is supported on both:
HFS v2.4 and
HFS 3)
...is it possible to port forward on a mobile network
This is a very broad question (hard to answer question). Some mobile network operators use NAT, so the address you see is not directly pointing back to your device, while others block inbound port forwarding. It also depends on the device you use to connect to the mobile network (it's not the same thing using an Android or iPhone, than some 4G LTE USD dongle). Even if you say what device you use, your mileage may vary. If you have some networking knowledge, in case your mobile ISP blocks port forwarding, what you probably need is a reverse tunnel (it can be done doing a reverse SSH, and for that you need to rent a VPS). You could follow
THIS guide if you are skilled with Linux. That's all I can help (covering all the details, gets too technical). Hope this helps.
