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Wifi DNS problems with TC8717T

I am having problems with my wifi on my TC8717T modem.  I use its wifi.  I am having problems with the wifi dropping my computer.  I suspect it is a software problem.  I changed the lease time to daily and for a week I finally had no disconnects.  Today, they are back.  Is there a way to set the DNS server to something else as the errors I get are DNA related?

 

When I am disconnected on wifi, my ethernet is still up.

I also don't get logged out of my teleconference sessions so the wifi isn't actually down.

 

Wifi signal is fine, strong enough and no interference

Wifi signal isn't near other signals - checked that already

Ethernet stays up when wifi is down

Signal strength is no different when wifi is up or down.

DNS is what is down, nothing else.

Wifi on multiple devices but not ALL devices is impacted.

Devices don't have this problem on other wifi.

5 REPLIES 5
Proven Sharer

Re: Wifi DNS problems with TC8717T


@IRKhelpme wrote:

I am having problems with my wifi on my TC8717T modem.  I use its wifi.  I am having problems with the wifi dropping my computer.  I suspect it is a software problem.  I changed the lease time to daily and for a week I finally had no disconnects.  Today, they are back.  Is there a way to set the DNS server to something else as the errors I get are DNA related?

 

When I am disconnected on wifi, my ethernet is still up.

I also don't get logged out of my teleconference sessions so the wifi isn't actually down.

 

Wifi signal is fine, strong enough and no interference

Wifi signal isn't near other signals - checked that already

Ethernet stays up when wifi is down

Signal strength is no different when wifi is up or down.

DNS is what is down, nothing else.

Wifi on multiple devices but not ALL devices is impacted.

Devices don't have this problem on other wifi.



It's important to remember that precision is your friend here in the user forums, rather than obscurity.  You will have to be more specific in describing your DNS issue:

You reported "When I am disconnected on wifi, my ethernet is still up." and "I also don't get logged out of my teleconference sessions so the wifi isn't actually down."  But then you went on to say "DNS is what is down, nothing else." and "Wifi on multiple devices but not ALL devices is impacted."

 

Don't confuse DNS with DHCP.  DHCP pertains to your local LAN, while DNS is used for routing at the remote end of the connection.  DNS is not a WiFi-only function, it includes all wired devices connected through your router to the internet. 

 

What is the adressing plan for your LAN?  [HINT: Most will be 192.168 1.n  (255.255.240.0), with the router at n=1]

 

If the DHCP is failing or improperly configured, you will get DNS errors because your computing device cannot find any DNS servers.  The big exception will be telecom services running over a VLAN service which have a hard-coded remote end IP address.

 

DNS is not just a WiFi function, it also includes all wired devices connected through your router to the internet.  

 

How many devices are you trying to run over WiFi?  You understand that Spectrum only allows 15 WiFi device connections on most of their routers. 

 

What SPECIFIC devices are being disconnected?  Smart phones, printers,video cameras & servers, home automation? Provide the make and model number for each one.  Which are wired and which are WiFi? 

 

Are any devices using VLANs which use hard-coded remote addresses? Which devices and what VLAN service?

 

What remote site is each one trying to access when its connection drops?  Give us at least the site name or the IP address; if you know both, we need both.

What local LAN addresses are the failing devices being given by the router's DHCP client? 

 

 

Sharer

Re: Wifi DNS problems with TC8717T

Have you tried manually setting DNS server addresses on your devices/router settings?

Ran into some similar weirdness this past weekend at my daughter's apartment in the Clemson area (NCTV market).

At first, DNS was only working on 1 laptop and 2 phones. Then one laptop started resolving some addresses, but key ones like google, malwarebytes, etc. were failing. Then they went AWOL again. Her roommate's laptop started saying no internet intermittently as well. Same things started happening at her boyfriends apt. on the other side of the complex as well. Something was knackered up either in their local intranet or at the ISP's level.

Ultimately had to manully set everything to cloudflare and Google DNS (1.1.1.1/1.0.0.1 and 8.8.8.8/8.8.4.4) and flush caches (ipconfig /flushdns from a windows command prompt). And yes, I did it on the router's internet properties page as well so the phones/rokus/etc. would use them as well. Note some devices need to have power cut from them for a few minutes to be sure caches are flushed (game consoles and such).
Rookie

Re: Wifi DNS problems with TC8717T

I apologize.  I am trying to be as precise as a learning layman can be.  I haven't managed to pull a log successfully showing the IP vanishing.  I need to figure out where to look to show that happening.  That is the one test I can't figure out how to determine.

 

I can say what has improved issues but not cured them:

1. increasing my DHCP lease time over the original hour that was the default setting

2. I have reserved the IP address for my laptop on wifi

3. In case interference or channel jumping was an issue, I scanned for wifi, determined the most empty channel, and set it manually to the empty spot for both 5 ghz and 2.4 ghz.

4. I verified wifi levels and wifi interference levels and they seem OK per the measurements on the app that is pulling data.

5. My address plan starts at 192.168.0.n (where n>100) as bumping that was advised and seems to help. (The default was 192.168.0.n)

 

These fixes have helped when the 4 tech and 4 line maintenance visits did not.

 

What isn't working my windows laptop, iPhone, TV, and mac that are on wifi.  They can't do email , get videos, or go to ANY website when this cycle of dropping starts.  I use Blackboard Collaborate for work.  About half the time it stays connected and in my meeting with no lag or latency problems when I am getting no DNS/no Internet warnings and websites become unavailable.  This isn't 100% but it has happened multiple times.  Blackboard Collaborate is a Java app.  I don't know what it uses to reach the outside world.  I just know I can have what seems to be no internet through wifi and my teleconference is uninterrupted with audio, video, and text chat very much intact. The Java backbone doesn't give me any indications on what IP it heads to or what it is doing other than connecting, lagging, or disconnecting me.  I would give you the server address if I knew it.  I don't.

 

I should note, I can sit right next to the box and this happens.  It also wipes out 2.4 and 5 ghz simultaneously.  That ruled out a lot of things in the eyes of the in-person and on phone tech support.

 

The wifi issues come and resolve without a reboot.  However, a reboot, since upping the lease time, seems to make the box stable for a longer period of time.

 

What works when the problems are apparent?  My computer on ethernet.  It has 0 glitches.

 

There is no pattern to the drops.  They happen constantly when the box freaks out.  I managed to go 10 days sans reboot after I made the changes above.  Prior to that, I couldn't even go 1 hour sans reboot.  The DHCP lease extension had the largest impact on my successful uptime.

 

I am fairly certain at this point that it is something in the software of the box.  The reason I am hypothesizing the DHCP is simply that changing those settings has been the most successful in remediating the problems.  ()Also, testing software, lines measurements, and 8 techs show no obvious issues.)

 

As I said, I am very new at digging through this stuff, so I apologize for my impreciseness.  I am giving you as many details as I have about what has replicated, improved, or briefly ceased the problems at this point.

Rookie

Re: Wifi DNS problems with TC8717T

I set my DNS on my mac to 8.8.8.8 and that didn't keep it on yesterday.  I was hoping maybe it would.  It went down just like the devices still on Spectrum DNS.

 

I would love to try setting the DNA server at the router level to see if it does help.  I initially get DNS errors when stuff goes haywire.  I can't see any place to do that in my box's settings.  If you know where they are, it would be much appreciated.  Eliminating another thing brings me closer to sanity.

Sharer

Re: Wifi DNS problems with TC8717T

Not familiar with your router, and haven't touched a mac in AGES... so basically bouncing some thoughts in general here.

As to setting DNS for the router, it should be with the core IP settings for connecting to your ISP. May be a dedicated WAN section. May be a general Connection section... each brand will note things differently. But it will have details about how you connect to the internet... likely will be settings about getting the config automatically from your ISP. It may also be displaying the IP address, subnet, and Gateway details it has been given from the head end. In that part of the page there may be a checkbox about getting DNS addresses from the ISP that needs to be toggled to manually enter addresses. Here is an example from an Asus router demo... note the Yes/No options for DNS. Setting it to No allows you to enter addresses:

https://event.asus.com/2012/nw/dummy_ui/en/Advanced_WAN_Content.html

Could probably rule out the DHCP server stalling and such by setting the IP address statically on the device itself... make sure it matches the one bound in DHCP so it doesn't cause any conflicts though.

Just to clarify... is the actual wifi connection itself dropping? Or is it just not resolving addresses through DNS?

Can try pinging the DNS server directly by numerical address (ping 8.8.8.8 for Google DNS) when it is messing up. If it communicates with the server, then wifi is still up (unless you are failing over to ethernet) . I guess we need to clarify that as well... is the system having issues only using wifi, or is it connected to Ethernet at the same time? If both, you may have an issue with the metrics assigned to each connection... if the system isn't prioritizing them right, there could be some weird things going on.

If you can ping the server by IP from a command prompt/terminal window, but can't resolve addresses in a browser, then something may be somehow blocking port 53 traffic (like a firewall, VPN settings, etc.), or something more malicious may be going on... possibly at the browser level. Something could have set a proxy address in the internet settings to filter queries, and it has gone off the rails. This has been known to happen with browser toolbars before... search bars, shopping assistants, site safety scanners, etc.--they may work by directing traffic through their own servers to filter (or even force) content delivery.

While in the command prompt/terminal window you can try a nslookup for a website to see if it works from outside the browser. Not sure if it is the same command in the mac environment, but seem to recall it was also nslookup in linux so it may be:

nslookup www.google.com

If this finds the IP when the browser does not... Then you may need to take a closer look at what is going on with your browser. A good malware scan may be in order.

Should note that some routers may have a section with network tools also. Both ping and nslookup should both be available there if they have such a section. On my Asus router, it has a drop box for picking each test, and there is a text box for typing in the address for running the tests. Again, here is an example from that router demo:

https://event.asus.com/2012/nw/dummy_ui/en/Main_Analysis_Content.html

This could be useful in ruling out a particular system as a whole... if DNS works fine from the router when not from a wirelessly connected device (as in that device can pull up the router' s GUI over wifi), it may not be the router having issues but something more specific to that device (provided the router' s firewall/filtering/PTP-VPN is not blocking the traffic on port 53 or any of the relevant addresses).