adding rules for OpenVPN breaks user-panel login

I don't have a slightest idea how this is related to each other, but when i add iptables rules to the FORWARD chain and nat table POSTROUTING chain through csfpre.sh/csfpost.sh, they break user panel login (2082, 2083 ports): when you enter valid credentials login page just reloads.
Here are the rules:

Code: [Select]

iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE
iptables -t nat -A POSTROUTING -j SNAT --to-source 12.34.56.78 #real server ip is here instead