Hello,
Could you clarify why you believe that this could be related to the firewall?
Do the devices show up as offline? Perhaps they actually lose the internet connection?
Generally, for firewall troubleshooting command iptables is used with its arguments. For example, iptables -L lists all of the rules used by the firewall to determine what to do with the packet. To get all of the available iptables commands, use the command iptables -h.
To restart the firewall, command /etc/init.d/firewall restart can be used.
Best regards,
DaumantasG