Frequent Visitor
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9 Messages
Consistent Comcast DNS Issues
To start off with I'm an career IT Systems Engineer, so bare in mind that asking things like "make sure it's plugged in" and "try restarting your computer" are not necessary......
I switched from Comcast Business for home office internet to Comcast Residential about 8 months ago when I moved and had the opportunity to get Xfinity Gigabit. I went the whole nine yards, I got the XFi XB6 gateway, I got the Xfi Pods. When I first setup everything, I was super happy and never looked back.
Fast forward to about November and all the sudden I've noticed consistent drops in my internet connection. The gateway is accessible and even the diagnostics on the gateway reflect that "everything is working fine" but it's not and I cannot figure out a resolution. When the network suddenly stops responding I am not able to resolve any dns lookups. So pinging google.com returns host not found but pinging 8.8.8.8 responds instantly. If I use the gateway diagnostics to ping www.comcast.net though it will work about 70% of the time, usually though the issue resolves itself about the time I get to the gateway to investigate.
This happens at all times of the day, I've seen it in the mornings, afternoons, evenings and middle of the night. Usually it resolves itself in a matter of minutes but soemtimes I have to reset the wifi and router modules using diagnostics, once in a while I have to restart the gateway using diagnostics, once in a blue moon I have to power cycle the gateway.
I'm wondering if this is a documented issue or if there's something I can do about it? I noticed with XFi that I cannot change the DNS, I'm 95% sure that's because a lot of the parental controls and filtering facilitate the functionality using DNS. While yes, I could set static DNS on devices other than my kids, that's not ideal of course. I spent a lot of money on getting all this setup and getting the equipment. I really don't think it was ethical for Comcast to make me buy proprietary wifi mesh pods when I cannot buy a gateway but that's another subject....
Looking for thoughts or suggestions before making a call to customer service or making a formal complaint.
jhynds
Frequent Visitor
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6 Messages
5 years ago
Hi, I am experiencing the exact issues, intermittent DNS outages are the symptom I am experiencing. Likewise, I've been in data/telecom for 30 years, so I don't think it's a simple pc or home router issue. This is quite frustrating during the day. Sometimes it self resolves in 5-10 minutes and if not I have to hard reboot the GW. I am using all IPV4 and IP pings to 8.8.8.8 are always good. My router (ASUS) also reports the WAN cable as disconnected, but the pings to the WAN IP still work.
Have you been able to resolve this issue? Any tips would be appreciated!
-Thanks
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jhynds
Frequent Visitor
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6 Messages
5 years ago
UPDATE
It just happened again.
I went into the GW GUI.
I Navigated to Troubleshooting, Reset/Restore Gateway, RESET Wi-Fi ROUTER.
This resolved the current DNS issue and it only took 90 seconds.
It does point more to the GW than any other components on the net.
It's not a FIX, but at least I can get back in the net faster.
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b_777
Frequent Visitor
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5 Messages
5 years ago
Following. My parents are having intermittent issues. Windows Remote assistance won't connect, and other screensharing websites won't load when they have this problem so I can't do much troubleshooting. At least mail server hostnames resolve, or are cached, as mail does work. Hopefully someone in this thread will have a great solution. I'd really like to be able to change their DNS to resolve against OpenDNS. They've got the Comcast combo modem/router.
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XfinityKenF
Official Employee
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8K Messages
5 years ago
If you're seeing drops and unresolved DNS issue on your Comcast modem, there might be some signal issues at the premise. Let's investigate.
All if you are seeing these issues, please send me a private message with your full name for help.
Ken
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b_777
Frequent Visitor
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5 Messages
5 years ago
Thanks Ken. My parents contacted support, and a tech actually replaced the modem. The tech said it had a good signal. I'm going to check it out to make sure it isn't a problem with their computer, and then will re-engage you/support if necessary. I was just looking for recent threads on DNS, since that seems to be the root of their problem. I was finally able to talk her through changing DNS to 8.8.8.8 as a test, but unfortunately, that didn't fix the issue.
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XfinityKenF
Official Employee
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8K Messages
5 years ago
b_777, appreciate the update. Was there no change after the modem swap? Looking forward to your update.
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jhynds
Frequent Visitor
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6 Messages
5 years ago
Sorry, you indented to communicate a different user and got me instead...
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glmonson
Regular Visitor
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3 Messages
5 years ago
I have the same issue with "resolving host..." on Xfinity Blast internet with new Arris SB8200 and TP-Link Archer A9 wi-fi router. I suspected cable wiring issue and Xfinity sent out a tech to review connections. Problem still there. Suspected SB8200 cable modem and swapped that out. Problem still there. Replaced TP-Link router and problem still there. Very intermittent and appears whenever our laptops have been inactive for 10 or 15 minutes. Constant 'reload' of browser eventually resolves the host name. Streaming video over Roku for hours is never a problem. Always rock solid video. Laptops are HP Win10 and Dell Win10.
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XfinityKenF
Official Employee
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8K Messages
5 years ago
glmonson, thanks for posting! Are you only having the issue on the Laptops? I know you said you're seeing drops on the Roku but are you seeing any issues on your cell phone for example?
Ken
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glmonson
Regular Visitor
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3 Messages
5 years ago
Resolving host (DNS) issue is on LAPTOPS. Both Dell and HP.
The ROKU streaming video is always good with no issues.
"Streaming video over Roku for hours is never a problem. Always rock solid video."
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bino2
New Poster
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1 Message
5 years ago
I'm glad I found this post because I also have the same issues. I've been a sys admin for 15+ years and it smells like a DNS issue. It's not the Chrome glitch either. I have a netgear CM1000 and thought perhaps that was the problem child. Come to find out users with an Arris SB8200 are having the same problems. I've done all the standard stuff, flushdns, reset, winsock reset, rebooting the modem etc. It's random when this occurs but very frustrating. Yes I coud try setting DNS static but how many of your customers would know how to do this. They are paying a pretty high price for your service. I have Performance Plus with Gigabit Internet , Win 10 1903, Cable modem Netgear CM1000, Router Asus ASUS RT-AC1900P.
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jhynds
Frequent Visitor
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6 Messages
5 years ago
@bino2
I also have a RT-AC1900P (Firmware Version:3.0.0.4.384_45717) and it is hardwired (5' Eth Cat 6) to my Comcast GW. The ASUS is the front end to my entire LAN. Rebooting it does not solve the problem, but rebooting the Comcast Cable Modem does.
Also, what I think is the same issue is with my Samsung TV hardwired to the Comcast GW.
Maybe the ASUS is screwing up the GW?
Are you seeing similar?
john
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glmonson
Regular Visitor
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3 Messages
5 years ago
Streaming Roku is rock solid. If either laptop is inactive for 10 or 15 minutes the wifi link stays up but no internet connection. Then, no DNS resolution until we try 8 or 9 reloads and then it links up to the internet. Switched cable modems, switched wifi router and replaced CAt6 cable between modem and router. Really think the issue is with Comcast Blast service.
Using Chrome and Firefox both lastest. Win 10 on both. Mcafee firewall on one and Windows Defender on the other. Both behave the same/
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jhynds
Frequent Visitor
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6 Messages
5 years ago
I have noticed my Netflix and Amazon streaming moves work great if they start when there are no issues with other devices. Once the DNS complete the lookup streaming does not use DNS. I have seen issues where Netflix or AMmzon(on Samsung TV) can't connect to their service, just like my PCs/Mac's and once I reboot the GW, all is well.
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XfinityKenF
Official Employee
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8K Messages
5 years ago
Hey Folks, if you're still seeing drops in your connection and would like me to take a look, just let me know. Please send me a private message with your full name for help. Just click my name (ComcastKenF) and then on the next page, you'll see an option to send a private message on the right.
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