Make sure that when you forward the ports to enable Both connection methods meaning you should have TCP and UDP enabled. Secondly, disable the Firewall because if unknown packets are requested through the IP, the Firewall on the modem might block them.
On your router/modem, it should look like this:
-
Remote host: EMPTY
Local IP: 192.168.1.77
Connection: TCP/UDP
Port range: 80-80
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Remote host: EMPTY
Local IP: 192.168.1.77
Connection: TCP/UDP
Port range: 6036-6036