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Saturday, January 27th, 2024 3:16 AM

Port forwarding getting ACK then RST and failing

I am having the same issue reported by hundreds of other customers. I am trying to expose the port 3000 of my internal IP 10

0.0.243 but i am getting connection refused even after turning off the gateway firewall and adding firewall rules for port 3000.

I tried everything, spent hours with xfinity support, they sent a technician to replace the modem, and no luck...basically all the network computerd using fixed IPs are not available for port forwarding, and if i change back to DHCP I still get an ACK and then refusal (RST) by the host machine , which is in same network segment of the hosted  VMs. I can see that I am being terminated by the host machine, who sends this RST immediatelly upon receiving a request from an external ip. (Everyrhing works fine if the request comes from an internal ip). I am wondering if I need to buy my own router or if I need to cancel my Xfinity contract and go somewhere else. I am blocked for 3 days now and need immediate assistance.

Thanks,

9 Messages

4 months ago

I tried with xb7 and xb8, and have the same issue.

Official Employee

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955 Messages

4 months ago

Hello @user_tseuv3 ,Thanks so much for taking a moment out of your day to leave a post on our community forum. Are you still having trouble with your port forwarding concern?

9 Messages

Yes... XB7 and XB8 both use xfinity app to do port forwarding. It does it only based on the DHCP table, so if you have a computer with fixed IP in the network, you cannot forward traffic to it, as the router sees it as offline and  xfinity app doesn't add it to the list of connected devices... this is a bug...  And hundreds of people are complaining of it for 2 years already...Are you planning to fix it?

(edited)

9 Messages

Repro:

1 - set one machine network adapter to a fixed ip in the range of your internal network.

2 - go to the gatewat portsl and then to "devices".

Expected: computer device is connected

Actual: device shows as offline.

3 - go to xfinity app

4 - go to wifi-> equipment-> advanced settings->port forward

5 - add a new port forward

Expected: device shows up in the list of connected devices

Actual: device is not on the list of connected devices.

Official Employee

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1.3K Messages

Thank you for explaining what was happening, @user_tseuv3. According to our port forwarding support article - https://www.xfinity.com/support/articles/xfi-port-forwarding - if a device is set to a static IP, it will not appear on the list of connected devices.

 

"With xFi, you no longer need to set a static IP for devices you wish to port forward. xFi port forwarding relies on the devices getting an IP address from the DHCP. When adding a port forward, xFi will use the IP address from Dynamic Host Configuration Protocol (DHCP) to set the static media access control (MAC) bind and establish the port forward rule. - If you are unable to set a port forward for a device that is using a static IP, remove the static IP in the Gateway Admin Tool and then try again."

 

It sounds like this is intentional. I'm not entirely sure if this was done as a security measure, or if it was the best way to integrate port forwarding into the xFi app, but it only works on devices with DHCP.

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9 Messages

I think it could be on purpose, but the result is that users cannot use xfinity to host their own website, in case they have cross-origin API calls to another computer in the internal network. Same goes with docker based  setups.

The xfinity router resolves the internal IPs based on the MAC address, but web applications must do API calls to specific IPs, making it impossible to use those xfi routers to create the topology, when the API or DB server are in different machines on the network..

In my case, I bought the Arris Surfboard G36 (Docsis 3.1) up to 2.5gbps... However, upon installation, my internet speed went down from 1100mbps to 100mbs download and drom 55 to 5mbps upload... A newer modem than the XB8, showed in the list of xfinity reccommended gateways, but that me and other users are realizing that they are not really compatible with xfinity, or they join to an older xfinity pool.

Also, when you chose a BYOD, you loose the unlimited data, and it puts a limit on 1.2Tb... So, is xfinity forcing users who host their websites to move to business plans?

9 Messages

Do you have an idea on how to solve this issue? I tried to use the DHCP with "Reserved IP" but the port forward is still not working on XB7 amd XB8...I also bought another modem. The netgear Nighthawk CAX80 and will try it today. I will post here the result. If it could do the port forwarding while mantaining the high speeds of the XB8, it would be an option...but still has the 1.2T data cap imposed by xfinity... could you confirm what happens if i reach the data limit? Will I be charged? The speed will go down? Or it will block data until next billing cycle?

(edited)

9 Messages

4 months ago

@XfinityJamesC , thanks for the reply. I had 2 technicians coming here this week, as well as long hours of support, but my speed still at 100mbps... We activated 3 times, but it didnt work... I found a thread with someone with same issue on the G36. This person engaged with Arris support and they told him that Arris modems need to have Upload Power level above 45 (i don't remember the power level for downlosds) to perform well, otherwise the signal could get lower than the noise, causing lots of retransmission of packets... In fact, my WinPcap shows several retransmitted packets...this energy seems to be provided by xfinity on the Coaxial cable, so there is no way to modulate it on my side...So, XB7 and XB8 needs less energy(signal) to work or the new activation had put me in an IP linked to xfinity via another route, which has more noise/less power... One of the technicians took a measurement of my signal, and opened a ticket. I still don't have a diagnostic from the support. Will update here when I have it, so others may have some tips on how to troubleshoot issus with BYOD.

Official Employee

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955 Messages

@user_tseuv3, Thank you for letting us know, I appreciate it! Please keep us updated and let us know how is goes, so we can make sure you get taken care of. 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

9 Messages

4 months ago

So, i have tested both brand new  Arris G36 and The Netgear nighthawk CAX80, and both give me the same 5mbps upload... Surprisingly, I reactivated my XB7, and it immediatelly gavw me 110mbps upload... There is something wrong on Xfinity side... Unfortunately, the XB7 is not doing the port forwarding, even when I change the network adapter to use DHCP (when i do this, i see the device on the list, but it doesnt honor the rule...Now. I am stuck with a performing cable modem that doesn't do port forwarding, or the other modems, which can do the port forwarding but, somehow, are being capped on 5mbps upload .. Any ideas how to go about it? I like Xfinity and would like to stay on the family, but my options are running out...

Official Employee

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137 Messages

@user_tseuv3, have you attempted putting your Xfinity Gateway in bridge mode and using a router to see if the speeds are maintained? This link will provide more information on how to do this https://www.xfinity.com/support/articles/wireless-gateway-enable-disable-bridge-mode.

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

1 Message

3 months ago

Port forward will not work with either xfinity device or your own device. I have tried with their XBT modem, and netgear's CM1100 and CM1200. Somehow it worked with CM1200 for only one day and kept me in circles with agent chat, technical support call. Right now I am waiting for technical support executive since 1hr 15 min, but no response. It is better move out of this carrier. I tried with other leading provider, it is working there flawlessly in bridge mode with my own router. Help me get out this contract for no port forward service available.

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