I have the TC8715D Modem, and no additional device (i.e. router/switch). Internet comes into my house straight into this box, and then it handles the routing and firewall for the home network.
I also have a rule forwarding port 2202 to a local IP address. Which was working swimmingly for a while, but has since stopped. I've reset the router a couple times (not factory, just power-cycled, really) and the functionality has still not returned.
Fearing that 2202 may have been thrown on some kind of 'no-fly zone' by Spectrum, or fallen under some other kind of arbitrary ruling I wouldn't even begin to know where to look to find, I modified the listening port on the local device to use 3636. Then, back in the Port Forwarding, modified the rule to use that port instead.
In the Troubleshooting > Firewall Logs > Today, I see that the request is being explicitly Denied by the router. Now I know it's not something with the local device, but I cannot - for the life of me - figure out why it's Denying access despite the Port Forwarding rule set to Allow it.
So...I figured, I would delete the Port Forwarding rule (along with some older ones that have been disabled for a long time, and I do not need anymore). But when I try to delete a Port Forwarding rule, I get the following error message:
Error Converting one or more entries:
Error: Modem is in bridge mode, creating/removing the port forwarding rule are prohibited.
Now...oddly enough, I would get this error message for ANY rule I tried to delete over the past few days troubleshooting. But just now, when I went to replicate the error for accuracy in this post, I was able to delete 2 rules before getting the error on my 3rd attempt.
Why is this modem in bridge mode? What is it bridged with? I have no other devices. Furthermore, why is it blocking a port I've explicitly told it to allow?
Google searches haven't turned up much (other than a response from Spectrum support explaining that it's a better idea to dump your local device into the DMZ than to forward a port or two - which is...awe-inspiring), so I figured I'd check in these forums before engaging phone support, in case some magnificent person happened to be strolling through with just the answer I needed.
Many thanks in advance!