It was Firewall rules indeed.
On the Main VPN server the following rules needed for the VPN tunnels being created through it
$IPTABLES -A FORWARD -i tun0 -j ACCEPT # VPN TUN Interface
$IPTABLES -A FORWARD -i eth1 -j ACCEPT # Local LAN
$IPTABLES -A OUTPUT -j ACCEPT
$IPTABLES -A INPUT -i tun0 -j ACCEPT
$IPTABLES -A INPUT -i eth1 -j ACCEPT
And rules on the client network firewall initiating one of the VPN links (branch server)
$IPTABLES -A FORWARD -i tun0 -j ACCEPT
$IPTABLES -A FORWARD -i eth1 -j ACCEPT
$IPTABLES -A OUTPUT -j ACCEPT
$IPTABLES -A INPUT -i tun0 -j ACCEPT
$IPTABLES -A INPUT -i eth1 -j ACCEPT
$IPTABLES -A FORWARD -i $INTIF -s 192.168.99.197 -d 0.0.0.0/0 -j ACCEPT # For default DROP policy firewall, My own IP (LAN)
Thanks for not helping