@David-TP 

I have taken this up with support, sending log files and it never went anywhere.   Here are the images you requested:

I have not tried disconnecting the 2 M9Plus units but will try that next.   It seems random when it happens since it will go days without it going offline, then suddenly it will go offline for no reason.   Thanks for any help you can provide.   

  @David-TP I removed the M9 units and have only the X60's now.  Ran fine for a few days and then this morning, it did the same thing.   Internet dropped just like before.  Here is the debug log for that timeframe.

Mon Jul 15 10:36:55 2024 daemon.info camera_security[10470]: neigh online ---> mac: FC:67:1F:63:0D:D1(0.570000)
Mon Jul 15 10:36:55 2024 daemon.info camera_security[10470]: sched_check begin
Mon Jul 15 10:36:55 2024 daemon.info camera_security[10470]: sched_check end
Mon Jul 15 10:36:55 2024 daemon.info camera_security[10470]: state_check block state not changed, block=0
Mon Jul 15 10:36:55 2024 daemon.info camera_security[10470]: watchdog runing
Mon Jul 15 10:36:55 2024 daemon.info camera_security[10470]: state_check
Mon Jul 15 10:36:55 2024 daemon.info camera_security[10470]: sched_check begin
Mon Jul 15 10:36:55 2024 daemon.info camera_security[10470]: sched_check end
Mon Jul 15 10:36:55 2024 daemon.info camera_security[10470]: state_check block state not changed, block=0
Mon Jul 15 10:36:58 2024 daemon.notice nrd[16950]: estimatorPerformMeasurement: Do 11k measurement for FC:67:1F:62:FF:BB on channel 10 from serving BSS APId 255 ChanId 10  ESSId 0  
Mon Jul 15 10:36:58 2024 daemon.err nrd[16950]: estimatorCmnHandleBeaconReportEvent: Invalid beacon report for FC:67:1F:62:FF:BB
Mon Jul 15 10:36:58 2024 daemon.err nrd[16950]: wlanifBSteerEventsHandleBeaconReport: Can't find local reported BSS on band of channel 0 for BSS 00:00:00:00:00:00
Mon Jul 15 10:37:00 2024 daemon.warn miniupnpd[15147]: unsupported NAT-PMP version : 2
Mon Jul 15 10:37:01 2024 cron.info crond[5823]: crond: USER root pid 31044 cmd sh /usr/sbin/process_monit
Mon Jul 15 10:37:04 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@245]: Group address 224.0.0.251 is Local Network Control Block
Mon Jul 15 10:37:04 2024 daemon.notice nrd[16950]: estimatorPerformMeasurement: Do 11k measurement for FC:67:1F:62:FF:BB on channel 10 from serving BSS APId 255 ChanId 10  ESSId 0  
Mon Jul 15 10:37:05 2024 daemon.info camera_security[10470]: watchdog runing
Mon Jul 15 10:37:05 2024 daemon.info camera_security[10470]: state_check
Mon Jul 15 10:37:05 2024 daemon.info camera_security[10470]: sched_check begin
Mon Jul 15 10:37:05 2024 daemon.info camera_security[10470]: sched_check end
Mon Jul 15 10:37:05 2024 daemon.info camera_security[10470]: state_check block state not changed, block=0
Mon Jul 15 10:37:07 2024 daemon.err nrd[16950]: estimatorDot11kIterateCB: Timeout waiting for 802.11k response from FC:67:1F:62:FF:BB
Mon Jul 15 10:37:13 2024 daemon.notice nrd[16950]: estimatorPerformMeasurement: Do 11k measurement for FC:67:1F:62:FF:BB on channel 10 from serving BSS APId 255 ChanId 10  ESSId 0  
Mon Jul 15 10:37:13 2024 daemon.err nrd[16950]: estimatorCmnHandleBeaconReportEvent: Invalid beacon report for FC:67:1F:62:FF:BB
Mon Jul 15 10:37:13 2024 daemon.err nrd[16950]: wlanifBSteerEventsHandleBeaconReport: Can't find local reported BSS on band of channel 0 for BSS 00:00:00:00:00:00
Mon Jul 15 10:37:15 2024 daemon.info camera_security[10470]: watchdog runing
Mon Jul 15 10:37:15 2024 daemon.info camera_security[10470]: state_check
Mon Jul 15 10:37:15 2024 daemon.info camera_security[10470]: sched_check begin
Mon Jul 15 10:37:15 2024 daemon.info camera_security[10470]: sched_check end
Mon Jul 15 10:37:15 2024 daemon.info camera_security[10470]: state_check block state not changed, block=0
Mon Jul 15 10:37:16 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@258]: Group address 239.255.255.250 belongs to IPv4 Local Scope.
Mon Jul 15 10:37:16 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@245]: Group address 224.0.0.251 is Local Network Control Block
Mon Jul 15 10:37:16 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@245]: Group address 224.0.0.252 is Local Network Control Block
Mon Jul 15 10:37:16 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@245]: Group address 224.0.0.251 is Local Network Control Block
Mon Jul 15 10:37:17 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@258]: Group address 239.255.255.250 belongs to IPv4 Local Scope.
Mon Jul 15 10:37:17 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@245]: Group address 224.0.0.251 is Local Network Control Block
Mon Jul 15 10:37:17 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@245]: Group address 224.0.0.252 is Local Network Control Block
Mon Jul 15 10:37:18 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@258]: Group address 239.255.255.250 belongs to IPv4 Local Scope.
Mon Jul 15 10:37:18 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@258]: Group address 239.255.255.250 belongs to IPv4 Local Scope.
Mon Jul 15 10:37:19 2024 user.notice IMPROXY: INFO[imp_verify_multicast_addr@258]: Group address 239.255.255.253 belongs to IPv4 Local Scope.
Mon Jul 15 10:37:19 2024 daemon.notice nrd[16950]: estimatorPerformMeasurement: Do 11k measurement for FC:67:1F:62:FF:BB on channel 10 from serving BSS APId 255 ChanId 10  ESSId 0  
Mon Jul 15 10:37:20 2024 daemon.info conn-indicator: <31330300> Invoke led: conn[1]
Mon Jul 15 10:37:20 2024 daemon.info leds: Event: conn.offline
Mon Jul 15 10:37:20 2024 daemon.notice conn-indicator: Connectivity changed: ONLINE(0x0) -> OFFLINE(0x1)
Mon Jul 15 10:37:20 2024 daemon.info conn-indicator: Notify inet.down

Obviously there is a problem with the X60's and since nobody seems to be able to find the reason, I'm going to have to find another mesh system that actually works.   

Very disappointed.  

  @Brychance 

This log line:

Mon Jul 15 10:37:20 2024 daemon.notice conn-indicator: Connectivity changed: ONLINE(0x0) -> OFFLINE(0x1)

It says Main Deco lost Internet connection. It could be connection between Main Deco and modem, could be modem to Internet. Could be, unlikely but could be, an issue with X60 firmware.

If you want to give Deco another try, I am going to suggest you do the following: bring back one of M9 Plus and make it Main Deco. With X60s as Satellites.

There will be one of two outcomes:

1. That setup is stable - you now have confidence something is not right with X60 running as Main Deco.

2. M9 Plus loses connection with that same log line in logs - you should be looking at that. In no way Satellite X60s could influence Main Deco M9 Plus lose Internet link. It must be something with the link itself.

How to replace the main Deco with another Deco

  @Alexandre. 

Thanks for the quick reply.  At this point I have nothing to lose and will take one of the M9 Plus units and follow the instructions to setup a new Deco to be the Main Deco in case #2 of the instructions.  I have also verified with my ISP (Frontier 1GB) that they show no outages on their side, and before I had the X60's, it would NEVER go down.  So I'm confident that the X60's are at fault rather than the ISP.   I will swap them out and see how it goes for a few days and report back here with the results.  

  @Brychance 

I initially joined this conversation, because I had similar problem, but with M9 Plus. When I brought them to my home network, I started to notice frequent short outages. Deco M9 Plus LED will go red, Internet connection will drop.

ISP Tech support claimed they have nobody else in my area complaining, and that they can see and connect to my cable modem/gateway just fine.

Eventually, I made them admit it is problem on their end, after presenting technical data they can't refute. They sent technician and he fixed the issue, which were impacting my house Internet link only.

Adding Deco mesh to my home network was just a coincidence.

Even if yours is different case, even if bringing back M9 Plus stabilizes Internet link, it'll give you time to comfortably choose different brand of WiFi mesh, in case you decided not to stay with Deco.

When you do that, I would suggest to list all useful features of Deco mesh, even not obvious. For example, with Deco you can take any Deco unit and make it Main Deco, some other WiFi mesh brands have different hardware for Main and Satellite units. If their Main fails, you lose all WiFi mesh till you get a replacement.

Connection preference feature - could be handy for large scale mesh deployment (more than 3-4 WiFi nodes). Not all WiFi mesh brands support it.

When you put that list, check that your new choice does have these features.

  @Alexandre. 

Got around to adding the M9 to the mesh and settting it as the main deco.  So now it's just a waiting game to see if the internet drops again.  Honestly, the features about being able to use any unit as the main router is not that appealing since once it's setup, you just want it to work and not have to worry about swapping out the main router for another.  As far as the other features, most of the other brands support all that and from what I have researched, many have more and better features than the Deco.  Especially around support.  It seems TP-link has very little on that subject.  As I said, I have sent log files, asked for explainations for the daemon errors, and got nothing back.   So if the behavior is the same after this swap out with the M9, I'll just toss the whole lot in the trash and go with another brand.  I work from a home office and I get on Zoom calls with customers throughout the day, and cannot have an unreliable connection that randomly drops for no reason.  Since purchasing the X60's 6 months ago, they have been nothing but trouble and I wish I had not 'upgraded' from the M9 plus which I gave away except for a couple of nodes or else I would have just put them all back in place.  But I only have 2 and my home is too large and I have too many devices to support.   It's just very disappointing since I really liked the Decos when they worked.  I'll give it a week or two and see how stable this configuration is and go from there.  

  @Brychance 

I understand that you are upset with TP-Link Deco and maybe plan to move to a different WiFi mesh brand. I am not trying to stop you from doing that, but there is no an ideal WiFi mesh. Each has its strong points and deficiencies.

Whatever one you choose next, makes sense for it to have at least smart design decisions TP-Link made for Deco - so that it'll be as good or better than Deco. 

I have my own list of what I'll be looking from WiFi mesh if I have to move from TP-Link Deco brand. For your situation I also have recommendations, but I can keep them to myself if you are not interested, and they are not that critical after all. Except the one I mentioned and you replied:

"The feature about being able to use any unit as the main router is not that appealing since once it's setup."

Let me elaborate. You should have found how easy it is to swap Main unit in Deco mesh with another unit you have. Hardware failures do happen. Imagine you have WiFi mesh where Main unit hardware is different from other units in mesh and Main unit can't be swapped with one them.

Now imagine Main unit fails. If it is under warranty, RMA process could take days or weeks: ship defective unit to manufacturer, wait for replacement to arrive. Meanwhile, as you can't stay without WiFi when you work from home, you'll have to go buy new Main unit (or all set) to get WiFi back at your place. Annoying at least.

Suppose, after few years and out of warranty, Main unit fails. Pray to IT gods that this brand has new Main units compatible with rest of your WiFi mesh. If they are not, you will be forced to buy whole new set, and from the screenshot you provided I can tell it is a large set.

It is not hard to find WiFi mesh with interchangeable units, but I also saw WiFi mesh product where you can't.

--------------------

Features and design decisions like this worth to notice and put on the list of what you want from the next WiFi mesh. If you are going offline for hours and days just because Main unit failed, you'll vent your frustration at forum for that WiFi mesh brand, and I'll not be there to say "I told you so."

  @Alexandre. 

Well, just when I thought it MIGHT have solved the problem by the switch to the M9 for the main Deco, the same thing happened again.  

So this will be the end of the line for these things.   Just going to replace them with something that is more reliable.  

With their support being nonexistent, it's just not worth it anymore.  

  @Brychance 

That actually tells there must be something wrong with Internet link, but as you don't trust Deco mesh anymore switching to a different brand makes sense.

Three things I would recommend you to check your next WiFi mesh has:

1. Swappable Main/Satellite unit hardware, for reasons I already explained;

2. Tri-band, if you are concerned with speed drop on Satellite mesh units. If current speeds you have are OK for you, dual-band (often less expensive) can do, which means you don't need to pay attention to that feature in WiFi mesh specs;

3. Feature similar to "Connection Preference." While WiFi mesh units are supposed to connect to each other in optimal way, when your understanding of "optimal" is not the same as what implemented in WiFi mesh, you should be able to overwrite it.