How to let all traffic go through the router?
If for testing purposes you need to let all traffic go through, it is not advised to disable router firewall because it will disable NAT capabilities, remove routes and other rules, needed for some functions like VPN to function properly. It is more efficient to use following iptables commands to let traffic through:
Accept ALL connections - iptables -I INPUT -j ACCEPT
Forward all traffic - iptables -I FORWARD -j ACCEPT
WARNING - Letting all traffic through freely, makes yours connection less secure and more vulnerable, it is recommended to use it only for short time, while testing connection. Use it at yours own discretion.