Maybe ipv6 DNS issues:
;; ANSWER SECTION:
www.rebeltechalliance.org. 159 IN CNAME rebeltechalliance.org.
rebeltechalliance.org. 158 IN A 136.243.169.53
;; ADDITIONAL SECTION:
rebeltechalliance.org. 159 IN AAAA 2a10:e000:1::10
I'm not completely up to speed on ipv6 stuff but I can't get that AAAA address to resolve. If it is a valid address you may be running services only on ipv4 and the VPN could be using an ipv6 address where no programs are listening... I think?
Also if you run the whole host you may want to see if you need all of these services available or can block incoming connections to them.
21/tcp open ftp
25/tcp open smtp
26/tcp open rsftp
53/tcp open domain
80/tcp open http
106/tcp open pop3pw
110/tcp open pop3
143/tcp open imap
443/tcp open https
465/tcp open smtps
587/tcp open submission
993/tcp open imaps
995/tcp open pop3s
3306/tcp open mysql
8443/tcp open https-alt