Devices Keep Losing Internet Connectivity from Deco M9 Plus

Devices Keep Losing Internet Connectivity from Deco M9 Plus
Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-06-11 14:39:18
Hardware Version: V2
Firmware Version: 1.5.1 Build 20210126 Rel. 59387

We have a Deco M9 Plus (version 2) that we purchased from Costco (and which replaced an aging, but still functioning, Asus RT-AC68u), and which worked fine for about a week after running whatever stock firmware came with the device.

 

However, starting yesterday (June 10, 2021), and about a week after upgrading the firmware to 1.5.1 Build 20210126 Rel. 59387, I started seeing strange behavior.

 

First, certain devices would show as being connected to the main Deco, but would have no internet connectivity, while other devices connected to the internet normally. If I attempted to disconnect one of the non-connecting devices from, and then reconnect to, the wifi network, the device would either not reconnect, i.e., it would attempt to reconnect, but would ultimately fail, showing a globe icon rather than a wifi icon (a Lenovo Thinkpad laptop), or I would get an invalid password error (an iPhone 12).

 

A reboot of the client device (the Thinkpad or the iPhone) would not resolve the issue , although a reboot of the mesh system (whether a reboot of the main node, or of the entire mesh system) would resolve the issue.

 

However, this happened throughout the day, and it culminated with the entire network going down - devices would either be connected to the wifi signal, but would not get an internet signal, or the devices could not connect to the wifi network at all. Again, I did a full reboot of the mesh network. This time, I unplugged the Decos, waited about a minute, and then plugged them back in. This again resolved the issue.

 

Throughout the day, I checked the modem, but it showed a solid signal, although I do note that, of the 16 downstream channels on our modem, 10 channels have a power level slightly greater than +7dB (range of 7.1 to 7.7). Our internet provider (Cox) was not reporting any outages.

 

As far as the mesh itself, the main Deco is connected to the modem (SB6183) on the first floor, the second Deco was also on the first floor, but on the opposite corner of the house, and the third deco was upstairs in a central bedroom (house is about 2100 sq. ft.). In all three cases, the Deco was on top of a shelf, with no obstructions. Also, the Decos were connected to each other via wireless backhaul, as we live in an older home that is not wired with ethernet ports in each room.

 

The only changes to the mesh I made were:

(1) I set the LAN IP to 192.168.1.1 (from the default of 192.168.68.1, or whatever the default was)

(2) I set static IP addresses to 4 devices (a wireless printer and 3 IP cameras)

(3) because of the invalid password error, I tried setting the Primary DNS to 8.8.8.8 and the Secondary DNS to 8.8.4.4. (for IPv4), which was a solution I saw mentioned on the TP-Link forums

(4) I did port forwarding for the 3 IP cameras

(5) I reserved a TP-Link DDNS

(6) As noted, I updated the firmware about a week ago

 

As a note, I also set static IP addresses on our old Asus RT-AC68u (running two using AIMesh), and I did the same port forwarding rules, yet we were not experiencing the same kinds of dropouts we were experiencing yesterday with the Deco. I did have to run two routers in a mesh, as one of the rooms upstairs received a very weak signal without a second mesh node.

 

I also thought I had too many Decos, which might be causing some sort of unexplained interference, so I tried removing the second Deco that was on the first floor (so I only had two Deco's - one of the first floor and one on the second floor).

 

However, when we woke up this morning (6/11/21), none of the devices we tried (several iOS devices and an Amazon Echo Dot) had an internet signal, even though the devices were allegedly connected to wifi. Again, rebooting the entire mesh system resolved the issue.

 

P.S. - although my devices could not connect to the wifi network, I was able to connect to the Deco remotely. Specifically, if I disconnected my phone from the wifi, and just used a cellular signal, I was able to connect to the Deco via the Deco application, which showed the Deco as being online, which is how I was able to reboot the mesh system.

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17 Reply
Re:Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-06-16 22:33:09

@OCRibeye 

 

Please download and upload the following firmware if you continue to notice Deco units have a red LED light: link

 

The above new firmware could be updated through http://tplinkdeco.net, and there is an upgrading instruction in the zip file.

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Re:Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-06-18 17:09:08 - last edited 2021-06-18 20:02:42

@Tony, thank you for the response.

 

It's been nearly a week, but I think I resolved the problem by manually re-installing the 1.5.1 firmware via a wired (ethernet) connection. Since that time, I have not experienced any further random disconnects.

 

If those issues resurface, I will try the firmware you linked me to.

 

Thanks!

 

Edit: I spoke too soon. Shortly after I responded to your post, I lost wifi connectivity again, and I noticed one of the Deco units turned red, although it returned to green a minute later. Because of how quickly the light turned back to green, I did not have a chance to check the other two Decos, which were on a different floor.

 

While my laptop reconnected to wifi immediately, my iOS device (iPhone 12) would not reconnect for 20-30 minutes. In both cases, I did not reboot the Deco units.

 

Per your instructions, I installed firmware 1.5.1 Build 20210520 Rel. 40426. I did so using the Update Tool, and I made sure my laptop was plugged into the main Deco with an ethernet cable.

 

I will report back if this problem persists.

 

 

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Re:Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-06-28 03:49:28

@Tony,

 

After installing the firmware on June 18, 2021, internet was stable for a week. However, we lost internet connectivity three separate times on June 25-26, 2021. 


As before, our devices would show we were connected to wifi, but we had no internet connectivity. If I tried disabling, and then re-enabling, wifi, it would no longer connect to the wifi network. Only fix would be to reboot all three Decos.

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Re:Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-06-28 17:25:31

@OCRibeye 

 

For Cox a good Chennel power level is anything between -12 and 12.  As long as you are in that range you should be good.   SNR should be between 30-50.  One thing I would suggest checking since the WiFi is still there but internet is lost is the modem logs.  I would look for T3 or T4 timeout.  These indcate a line issue and will typically need a maintenance tech to plant to resolve.  These are items typcially not looked at by Cox support.  They typcially only run a connection test to see if service is reaching your node.  They don't show the line quality.  

 

That is where i would look at next.  

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Re:Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-06-28 17:47:29

@Carl 

 

Thank you for the reply. I checked the power levels (between +2.9 and +7.8) and SNR (between 43.1 and 46.0)

 

As for the modem logs, I do see one T3 timeout, although I see a number of these errors.

 

* SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing

* SYNC Timing Synchronization failure - Failed to acquire FEC framing

 

Also, for the "Time" column, it is showing "Time Not Established."

 

As for your other comment about a line issue, Cox replaced the line from the street to our house within the last year. However, I will give them a call to see if they look into this further.

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Re:Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-06-28 18:40:07

@OCRibeye 

 

Ussually the line issues are at the plant, where the CTMS cards are located it ussally isn't the phyiscal line but rather hardware connected to the line on their end.  1 T3 shouldn't be an issue but if you are seeing errors and Synchronization faliures it might be good to have them check.  If you get a level 2 or 3 tech ask for an intrusive line test.  If you do just make sure you aren't doing anything online at the time as your connection will drop during this test. 

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Re:Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-06-28 18:43:09

@Carl 

 

Thank you for the response and explanation. I will monitor the modem logs in the next few days, and will call Cox to have them run the tests you suggested.

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Re:Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-07-14 02:45:37

@Carl

 

Modem logs have looked totally normal (no T3 or T4 errors), yet the Deco went down three days in a row (twice today). I also tried rebooting the cable modem, and I switched the Decos around, so that one of the satellites is now the main router, but I lost internet connectivity again a few hours later.

 

I also sent an e-mail to support@tp-link.com, and received a response from a senior engineer named Parker Hu, who offered to troubleshoot the issue, although he asked I download an application called awesun. Trying to connect with Mr. Hu to see if we can remotely resolve this issue, or at least figure out what the problem is.

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Re:Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-07-14 16:06:27

@OCRibeye 

 

Hello. Yes Parker is one of our senior system engineers and very knowledgeable.  If anyone can figure this out it will be him.  He is however in China so working with him would be after hours for us.  His day starts around 5-530 pm Pacific.  If you need help getting a session sceduled send me a private message with your contact infromation and what day and time works for you.  we would need at least a 1 hour window to call.  

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Re:Devices Keep Losing Internet Connectivity from Deco M9 Plus
2021-07-14 16:49:19

@Carl 

 

Thank you for the response - Parker and I connected last night, and he used a remote connection to run some diagnostics on the router, but he could not figure out why I continue to intermittently lose my wifi connection, as he confirmed I had a good signal.

 

He believes it may be a hardware issue, and he sent me instructions on how to RMA. Unfortunately, I am unable to register my product, as the TP-Link website does not recognize the serial numbers printed on the bottom of the Decos, or the serial number printed on the box. I have submitted photos of both serial numbers to TP-Link Support, along with the proof of purchase, and hope to get resolution of this issue soon.

 

 

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