port forwarding on customer owned modem

I have a router.  The port forwarding was working fine, and suddenly stopped.  Ping always worked before as well.

I know how to perform port forwarding.  Something comcast is doing is stopping it (as well as pinging).  The "advanced security" seems like a possible suspect, and the Overview says it's on, but doesn't give me any way to turn it off.  People on this forum claim to have gotten customer support to turn it off for them, but I can't figure out how to get a human customer support person.  The bot keeps asking me whether my connection is down or only slow.

OK, so if that's not what's blocking it, what is, and how do I turn it off?  It was working until a few weeks ago.

The modem is an  ARRIS (S33) - Cable Modem

The router is a tp-link AX3000 archer AX55

Thank you for the additional information. You would need to set port forwarding up through the router's interface. Usually, third-party routers like this have a login for you to use to be able to set up more specific features like port forwarding. We would suggest contacting the manufacturer to get assistance with this. We believe you had mentioned in your previous post that it was working previously, which tells us there is a possibility there may have been a firmware update and that may have caused it not to work properly.

I’m glad I am not the only person who is unable to make this work. I am unable to forward any ports on my owned equipment. 

I have experience with port forwarding in past. Just tried to do it with xfinity using my own modem and router. And it is not working. I know I am doing it right from my end. It looks like something on the xfinity side is blocking incoming connections. 

Just found this thread. Sorry for resurrecting it...

I, too, am trying to set up port forwarding with my residential xfinity Internet service. I just spent several hours on the phone with various xfinity support people, to no avail. They all seemed interested and tried to help, but ultimately could not.

My setup:

-Arris CM820A cable modem (customer-owned)
-Eero router (obviously customer-owned) with port forwarding correctly configured
-Inbound Windows firewall rule added for port traffic on PC where process is listening

Port forwarding doesn't work.

Running a traceroute from inside my network shows the first hop is my router (expected), but the second hop is a non-routable address (10.27.59.186):

tracert -d 8.8.8.8

Tracing route to 8.8.8.8 over a maximum of 30 hops

  1     2 ms     1 ms     2 ms  192.168.4.1
  2    17 ms    29 ms    17 ms  10.27.59.186
  3    21 ms    20 ms    18 ms  68.85.175.45
  4    23 ms    18 ms    17 ms  68.85.61.150
  5    16 ms    26 ms    17 ms  96.216.131.77
  6    16 ms    17 ms    17 ms  96.216.131.117
  7    23 ms    22 ms    22 ms  96.216.131.13
  8    23 ms    23 ms    22 ms  96.110.235.17
  9    23 ms    26 ms    23 ms  96.110.40.17
 10    27 ms    19 ms    23 ms  96.110.37.114
 11     *        *        *     Request timed out.
 12    21 ms    21 ms    22 ms  192.178.45.29
 13    21 ms    20 ms    22 ms  142.251.77.65
 14    23 ms    20 ms    23 ms  8.8.8.8

Call xfinity, tell them that I seem to be behind some sort of NAT and that I'm being routed to the Internet through a private subnet. Ask for a public IPv4 address.

Ok, no problem, we just need to switch your plan, but don't worry, it'll be the same cost. (Eventually) That's done, so just give it 24 hours and it should all be good.

48 hours later, no change. Contact xfinity again. Explain everything again. Is the problem with your TV service (which I don't have) or your Internet?

Talk to a different agent, explain the whole thing again. Sends me a link to a support article about using the app to configure wifi. Does this work if I'm not using xfinity equipment? Not sure, let me transfer you.

Explain everything again to the next agent. Have you tried the app? I don't lease equipment, can this still work? Not sure about the particulars of the network, let me send you to another group (after mentioning finding a different ISP).

Next agent: I can refresh your modem, or maybe you could try to configure the wifi with the app. I'll send you some documentation (same article as above). Will the app work without leased equipment? No. Have you tried connecting a PC directly to the modem? No, my laptops are too thin for Ethernet ports and I haven't dragged my desktop and monitor to the basement to connect to the modem. I understand--I'll transfer you to my floor supervisor.

Explain everything again to floor supervisor (nice guy, genuinely trying his best). Discuss connecting a PC directly to the modem. Disassemble/move/reassemble the PC in the basement, attach directly to Arris cable modem. PC gets a 73.200.x.x address assigned from Comcast DHCP. Ok great, try the tracert again. Now the first hop is the same 10.27.59.186 address (which makes sense, since the router is no longer in the equation). So routing to the Internet is still traversing a private subnet. Port forwarding still (obviously) doesn't work. Verified still not working (obviously) after turning Windows Firewall off completely.

Floor supervisor calls back, as promised (again, nice guy, trying to help!) I think the problem is your modem, try to call Arris and get them to help you set up port forwarding. I don't think that's the problem--it's a bridge modem, so can't route or do port forwarding, etc. Is there a T3 network engineering group I can talk to? No, just us floor supervisors. Ok, the Internet suggests asking having tier-2 provisioning or the CMTS group rebind my modem to a public subnet. Can we do that? No, but we could just reset your modem to factory defaults. Or you could try rebooting the modem (already have). Or call Arris and ask them to set up port forwarding on the modem.

Sorry--I know this is miserable to read. It was miserable to experience.

Has anyone, anywhere been able to set up port forwarding with xfinity service?