Hidden SSID channel conflict

[jbuchanangb]

It seems that my Sagemcom hub is radiating two Wi-fi SSIDs on the same 5Ghz channel. They have very similar MAC addresses, and when I changed the channel for my "known" 5Ghz SSID, the channel changed for the "unknown". This strong competing signal may be the cause of the occasional Wi-fi brown-out I experience, even though those also seem to affect the 2.4GHz channel.
Why would the hub be doing this, and can I turn it off?

Wi-fi channel analysis

[KeithFrench]

No worries, if you change your mind, let me know.

[jbuchanangb]

I'll just continue to live with it. I have drawer full of routers I could substitute if I felt like it. I have a DSL-3782 and and an HG533, both supplied by TalkTalk, and my Netgear WNR2000 which I bought way back when I first connected to FTTC and TalkTalk suppled the Huawei Modem along with some shoddy router with bespoke firmware which used one of the LAN ports as a WAN port. That would have been in March 2012 when I added "Fibre Optic Boost" to my existing  broadband.

Appreciate your interest and useful hints and tips.

[KeithFrench]

Hi @jbuchanangb 

The UI is very well known to stop responding in this way, it is supposed to be fixed in the next firmware release, but I am not sure when that will be. There is nothing in the log to suggest a problem at all, but of course, the UI is showing the internet is disconnected, but I guess that the UI stopped responding at that point & by the time you logged out & back in again, it was back up. 

Obviously, this looks like a problem with the router, PLAs or the modem. I think that this is the first time that the router has agreed in part, that the internet was down, but I was expecting something in the log for it as well.

I am on full fibre & going back to the last time I did a factory reset, these are similar entries to what I would think that you would get:-

01.01.2013 00:00:32	Info	DHCPC	The WAN DHCP client IP address x.x.x.x
01.01.2013 00:00:29	Info	DHCPC	WAN DHCP client (1) started
01.01.2013 00:00:29	Warning	DHCPC	WAN DHCP client (1) stopped
01.01.2013 00:00:29	Info	DHCPC	WAN DHCP client (1) started
01.01.2013 00:00:27	Info	WETH	WAN Ethernet connectivity has been established

Just to be on the safe side, would you like me to get TalkTalk to replace your router?

[jbuchanangb]

Here's the log for the preceding half hour, with filtering turned off.

Unfiltered router log

You can see me logging onto the router and everything else it has been doing for the previous half hour, while no-one was looking. I was watching TV on the YouView box.

In a further puzzle. Having extracted the above log, and reached the screen shown below. No amount of clicking on black or green "Home" symbols would return me to the router's home screen.

Router Wi-Fi display screen

Just says "We are loading your dashboard" and comes back to same place. I notice that top right it says "Internet: Disconnected", which at that moment, it wasn't! That of course might be a reference to the fact that there is no VDSL line connected to it. I don't suppose many people feed this type of router from a modem via PLAs.

The Logout button worked just fine.

This mystery is not urgent to solve, isn't ruining my life, I've been living with it for months, and willing to continue to do so.

[KeithFrench]

You can normally ignore all the DNS entries as the classification of them is wrong. They should be "Informational" not "Error". I am waiting for this to be fixed.

The router is, as you say, confirming internet access. Are there any non filtered stuff in the router's log that show anything to do with the wan going down or coming back up again? Perhaps it was all back up by the time you logged onto the router?

[jbuchanangb]

OK I was watching the YouView box, went to recordings list, noticed that the illustrations were blanked. That is a symptom of lost Internet connectivity. Headed to the office, Raspberry Pi display showed "No Internet". Lost internet icon visible in systray of PC. Logged straight onto the router which showed a good Internet connection. There was a short delay between the diagram showing on the screen with green from PC to router, and red from router to Internet, which then changed to green. Immediately drilled down to the system logs which were set to display "Error or lower". This is what there was.

Router log files

Systray icon changed to show strong wi-fi connection. Raspberry Pi display soon reconnected to display what it is there to display.

It's a puzzle.

[KeithFrench]

OK, your modem terminates the fibre, but if the WAN link has gone down, perhaps due to the PLAs, surely the router should know there is no internet access. My guess is that unless the downtime is very short, the router should know about it. Does the system log give any clues, or is the router faulty?

[jbuchanangb]

Maybe that's it. They are both warm to the touch. But they are installed in open well ventilated locations. I've had them since last June. The Netgears they replaced were over 10 years old. I have a choice - live with the occasional brown-out, or buy some better PLAs!

[KeithFrench]

I used to use exactly the same TP-LINK PLAs and they used to overheat & drop out. That was probably my fault as one was not in the most ideal location.

[jbuchanangb]

It's hard to know what is causing the brownouts. When they happen all the devices connected to the router lose Internet connection including the YouView box which is wired to the router. But as soon as I log in to the router using the wi-fi, which hasn't failed, the router displays that the Internet is OK. So yes, it may be the WAN link via the PLAs which is going down.
In the past, while the link has been down I have connected to "Test my Connection" using 4G, and the Connection test tells me my Internet is perfectly fine, by which time, of course, it is. A few months ago TalkTalk's Ady had a look from his end during a time window when an event had occurred, and he could see no problem.
Of course PLAs rely on some fancy technology to get the signal though the mains network. I am using tp-link model TL-PA4010 PLAs. I suppose they may be subject to some sort of interference. I used to have a pair of basic Netgear ones, but one them failed so I replaced them. 

When I saw the intermittent conflicting hidden SSID I though maybe at last I had found it. Just have to live with it.

[KeithFrench]

Hi @jbuchanangb 

I think that although there are the two SSIDs, crucially there is only one radio, hence why it follows the channel change. If you enabled the 5G guest network that will do the same. More expensive mesh systems use two radios so the backhaul SSID can use a different channel.

I expect that the reason the hidden one disappears after a while is that if it doesn't detect a 266, it times out.

Are you saying then that the WAN link via the PLAs is what is going down then rather than the WiFi?

[jbuchanangb]

How interesting. The hidden SSID shows up intermittently and goes away. Good to know what it's there for. inSSIDer Home is recommending I change channel to get a better signal to avoid the conflict, but when I did that, the hidden SSID followed me! The source of the brown-outs will have to remain a mystery. My current suspicion is the PowerLine adapters between the Huawei VDSL modem and the Sagemcom router. Their very odd. Just did it as I'm typing. PC lost the Internet, and simultaneously told me it had lost the link to the wi-fi connected printer. Other side of the room the Raspberry Pi has lost the internet. Obviously it's all come back or I couldn't have submitted this reply. Was only out for about half a minute.

[KeithFrench]

No, the two 5GHz SSIDs won't cause a problem with each other, nor can they interfere with the 2.4GHz band.

This hidden SSID with a similar BSSID has a very special function. You may not know this, but TalkTalk has launched a product called the Sagemcom "WiFi Booster" (FAST 266). Personally, I think that the name "WiFi Booster" does not do this unit justice. When combined with a FAST5364 or 5464 router, the two form a mesh network together. To maintain the 5GHz backhaul essential to mesh operation, each one sends the hidden SSID that it wants the other unit to connect to. 

From V158 firmware the routers always transmit this hidden SSID in case it detects a FAST 266, you cannot turn this off.