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dropping VPN connection through gateway on VOIP calls

WFH303
Regular Visitor

dropping VPN connection through gateway on VOIP calls

I have a leased xfinity/arris xb6 with phone attached set to bridge mode connected to orbi network. It seems that everytime I get a phone call, my outbound VPN connection to work drops and sometimes the internet drops on more than one computer. I saw some suggestions about disabling advanced security but it's my impression that it is not enabled when in bridge mode. I cannot even access the security settings from the app or browser in bridge mode. Same thing happens if I am hardwired to the router. As a final test, I connected to the XFINITY/xfinitywifi hotspot directly to bypass the router (and any firewall issues) and the same thing happens. It seems that VPN sees some change in the network and drops during a call or right after. It consistently happens with any in/out bound VOIP call. I do not recall this happening with an older/slower cable modem before I upgraded. 1gb vs. reliability......hmm. Any ideas or suggestions on what to try next? Cheers.

WFH303
Regular Visitor

Re: dropping VPN connection through gateway on VOIP calls

So I did a bit more investigating. From what I can piece together, there has been posts on this in the past but they are "archived" so all you get is the teaser text and can no longer get the full text! Too bad since it may have answered my OP. From what I can tell, the arris modems like the xb6 have a puma chipset that has a known problem. Another post references UDP packet filtering. An outside website states "The CPU takes too long to process packets under the increased load...". Sounds like the VOIP call triggers this load. It exhibits network latency and jitter which the VPN does not like. Search for "bad modems puma chipset" to find out more. I wonder if I can get comcast to swap out for another modem or do I have to buy my own?

ComcastThomasF
Official Employee

Re: dropping VPN connection through gateway on VOIP calls

While we don’t provide technical support for VPN connections, we've provided some helpful information here. If you need help setting up, using or troubleshooting your VPN connections outside of the details provided below, please contact your VPN provider.

 


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WFH303
Regular Visitor

Re: dropping VPN connection through gateway on VOIP calls

Thanks for the pointers. As noted I am running in bridge mode. Probably because of that there is no "Firewall" option in the menu. Under Home Network, it does state that Firewall Level is LOW. I am following all the suggestions in these links. Note that I connected to the public wifi side (XFINITY) and the same problem happens and none of this happened before I upgraded to this new modem. I do not suspect it's a config problem since I get VPN successfully until the VOIP call comes in. I would like to really switch to a CGM4140COM or CGM4331COM model modem from the TG3482G since most things I have read says that would solve the problem.

WFH303
Regular Visitor

Re: dropping VPN connection through gateway on VOIP calls

BTW, this is not just a VPN problem. I am dropping internet intermittently when phone is active. The VPN problem is what brought it to light. It does reset after a few seconds but I am forced to reestablish the connection. Pretty sure the modem is the issue.

ComcastLysaP
Official Employee

Re: dropping VPN connection through gateway on VOIP calls

I do appreciate all the troubleshooting you have done on your own to attempt a resolution. I can always double check and verify if a different offered modem will still be compatible with your services. Please send me a Private Message with your first/last name, name on the account if different, and full service address. 


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