help - trying to run under nat

[hacknorris-code]

so yes, i wanted to enable https for my homeserver (friend asked). im behind nat which doesnt support sharing all ports at once (i forwarded 3000 only cause its required for server i run) neither allows loopback. my server is misskey (runs under engine x).
someone knows how to use this certbot with blocked such things ? i followed all tutorial from misskey, only this to do...