You should allow both incoming and outgoing connections to the Air VPN servers
Unless you wish to send/receive traffic in only one direction, which will result in a very unusual experience
Sorry for asking this again and please forgive me for my ignorance.
For example commands for a single AirVPN server like:
iptables -A INPUT -s 188.8.131.52/32 -d 0/0 -j ACCEPT
Means allow incoming from source (AirVPN server) to any destination. It allows incoming connections from AirVPN server. This one looks fine to me.
iptables -A OUTPUT -s 184.108.40.206/32 -d 0/0 -j ACCEPT
Means allow outgoing from source (AirVPN server) to any destination. How can an AirVPN server be a SOURCE for OUTGOING from my router?
shouldn’t it be
iptables -A OUTPUT -s <Synology IP>/32 -d 220.127.116.11/32 -j ACCEPT
Also, I don’t understand how these two entries will stop outgoing connection to any destination from my Synology except for AirVPN servers as these entries are only allowing and not rejecting anything from Synology.