877w firewall and remote config issue

[mrak48]

Hello peoples probably a dumb question so applogise in advance .. I have a cisco 877w router I have managed to config the firewall and vpn and all is working fine the issue I have is after enabling the firewall I can no longer connect to remote access the router over the internet connection so I'm thiking that the remote access is being blocked by the firewall is there a specific port that needs to be let through the fire wall.

Thanks for any help

Dan