i am not sure that having private IP of certain class has anything to do with your issues
https://en.wikipedia.org/wiki/IP_addres ... _addressesafaik people just ageed to have certain private IPs just to avoid confusion. and you can force your PC and router use any other local IPs and it all still will work (or at least will work to some extend)
it is 1rst time i hear about private IP classes and it looks to me that it also should not have any impact on your connection.
There are few things you can do:
•Read red text above, and recreate issue while having "saving logs" enabled. and post logs here so we can try to help you. Prefererably logs of all players that have connection issues (there is only one guy that has connection issues so probably he has issues, but someone else should post logs too. Not only just in case, but also to see what is happening on other side)
•Double check port forwarding:
Try useing Downlords client (Alpha client) and check if it gives any errors about open porst
•Try useing UPNP: Use official client, make sure that UPNP check box is enabled in port settings. test again for connection issues.
Note that If you have two people in same local network (using same internet) then you have to use different ports, port can be changed in lobby settings. and both ports will have to be open.