Hello!
All problems were resolved. For the readers:
YuNoGuy problem was caused by the Windows Firewall blocking the incoming traffic of other programs his/her main listening program relied on. Check the message here for interesting and useful details: https://airvpn.org/forums/topic/56970-port-forwarding-connection-timeout-error-110/?do=findComment&comment=227771
JebediahWolfe (original poster) problem was caused by the fact that the remotely forwarded port was disabled by the user in the control panel. All ports are enabled by default when you reserve them to your account and a new option allows you to disable them without de-allocating them. It is an option which can be useful under specific circumstances and required by some users. Always pay attention when you change settings.
Voja Ten. problem "disappeared by itself" from one day to another so we can't say anything about it.
Kind regards