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08/29/2026 11:34 PM

I still don't have an open NAT type after enabling UPNP

Hello,

I'm having infrequent issues when I'm gaming like random packet loss and disconnects and decided to investigate my NAT type, which apparently is a Port Restricted Cone NAT type, and I thought that might be the source of some of my problems so I decided to change it to be open. Everything I've looked up online seemed to indicate that making sure UPNP was enabled (which should've already been enabled but for some reason it turns off by itself randomly), making sure I don't have a CGNAT or a Double NAT, and a few other small things means I should have an open NAT, and yet I don't. Is there anything I'm missing here? Do I need a new modem perhaps? I'm on an XB8 and thought about upgrading soon for this reason.

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EG

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121.3K Messages

21 days ago

FWIW, UPnP is a security risk. Manual / individual port forwarding is always preferable. It is disabled by default in the Xfinity-rented gateway devices, and apparently it is deliberately returned to that state when the device reboots / updates.

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user_miq0ha

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I'm confused why the option is even there at all then if they are just going to disable it without my consent anyways, I'd heard the return to being disabled was a firmware bug.

The problem with individual port forwarding is that I have to enable that for every individual game that I play, and also have to hope that I can find out which ports I even need to open. UPNP is far more convenient. I've also seen mixed opinions on just how much of a security risk it is so idk.

I guess the only solution then is to just get my own modem and router that won't disable it.

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21 days ago

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EG

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That's of course your choce but it doesn't change the  fact that it is still  a potential security issue. 

(edited)

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21 days ago

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XfinityJohnG

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Thank you for reaching out to our team with that question. @EG is correct about the security aspect of that set up. If you need us to look further into your account, or make any changes on the service and equipment we are happy to assist you from here. 

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20 days ago

user_miq0ha

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I'm a little confused by this conclusion, since surely if UPNP is a security risk then using port forwarding manually is also a risk too. Either way, it seems like that's the way it is.

I'll do some research on if I should get a seperate third party router. If I do, then I can just put my Xfinity modem into bridge mode correct?

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14 days ago

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EG

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@user_miq0ha​ wrote;

I'm a little confused by this conclusion, since surely if UPNP is a security risk then using port forwarding manually is also a risk too. Either way, it seems like that's the way it is.

UPNP opens up the entire world. Port forwarding only punches one hole in the firewall. That is far safer, no ?

I'll do some research on if I should get a seperate third party router. If I do, then I can just put my Xfinity modem into bridge mode correct?

Correct.

(edited)

I am not a Comcast Employee.
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We ask that you post publicly so people with similar questions may benefit from the conversation.

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14 days ago

EG

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14 days ago

@user_miq0ha 

My pleasure !

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user_miq0ha

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7 days ago

So I ordered a 3rd party router, TP Link if the brand matters, set up Upnp, even tried setting my PC to be in a DMZ just for diagnostic purposes and no matter what I do I cannot get an open nat type on PC. I am confident the xfinity modem is in bridge mode so it's not a double nat situation, my ip address is public so it's not a CGNAT situation, I have no idea what is stopping me from having an open NAT.

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XfinityDena

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@user_miq0ha Just checking in. Are you still in need of assistance after being assisted by @Again?

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2 days ago

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EG

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@XfinityDena​ 

It's EG...

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2 days ago

user_miq0ha

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@XfinityDena​ Yeah I'm really confused as to how I can have a port restricted cone nat when I've set everything up to be open, UPnP is on, I don't have a double NAT or CGNAT as far as I can tell, so I'm confused as to how this is happening.

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6 hours ago

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XfinityThomasC

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Sorry for the confusion, I'll tag @EG in on this, so you can continue your conversation. Could a step have been missed in enabling UPnP and Port Forwarding or rather order of steps? 

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6 hours ago

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