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Router getting "Concentrator unreachable"

GrahamClark
Dabbler
Posts: 21
Registered: ‎14-05-2013

Router getting "Concentrator unreachable"

Hi, this is just a FYI with a couple of questions.
I had an issue yesterday Sun 1st June about 3-4pm. My TG882n Fibre Unlimited router was getting " concentrator unreachable" or something similar on trying to connect. My BT modem had the DSL green solid and was OK. I phoned your support team and I connected one of my laptops to the modem via PPPoE and it worked OK, normal high speed 73Mbps/18Mbps/13ms ping. Going back to the router it was still failing with the same message. The support representative said he would send out a new router.
Later that evening I looked at the Plusnet status ( via my still working Virgin cable link ) and noticed an outage "Broadband connectivity (75522)" and thought I'd try to connect again. Lo and behold the router connected!!!
i) I presume my router is not faulty. What do I do with the replacement router when it arrives?
ii) I suspect that the TG582n router handles PPPoE slightly differently than does my Windows 8 laptop. Maybe longer timeouts,? Anyway I guess a laptop via PPPoE is not conclusive in proving a router faulty; or is it?
Graham
40 REPLIES
Plusnet Help Team
Plusnet Help Team
Posts: 13,542
Thanks: 252
Fixes: 69
Registered: ‎27-04-2007

Re: Router getting "Concentrator unreachable"

Hi there,
This can happen if the line is disconnected "ungracefully" i.e disconnected suddenly on some part of the network and it can means that it takes a little longer to reconnect or may even need the FTTC modem to be rebooted before it reconnects.
Quote
The support representative said he would send out a new router.

Quote
i) I presume my router is not faulty. What do I do with the replacement router when it arrives?

Oops, it's a modem error so I've no idea why we did that, feedback on the way to the agent and when you receive the replacement there'll also be a postage paid returns bag, send the new one back if you prefer, it's up to you which you'd rather keep.
Quote
ii) I suspect that the TG582n router handles PPPoE slightly differently than does my Windows 8 laptop. Maybe longer timeouts,? Anyway I guess a laptop via PPPoE is not conclusive in proving a router faulty; or is it?

It is infact the Opereach modem that handles the connection timeout settings differently so that's something you could look at, however if that is continuing to happen it's a known type of fault that we need to look at for you so keep us posted. However I've noted that all this happened around the time of a widespread outage so it may well just have been that, really sorry for the hassle either way!
Adam
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
GrahamClark
Dabbler
Posts: 21
Registered: ‎14-05-2013

Re: Router getting "Concentrator unreachable"

Thanks Adam.
I'm still not sure why my laptop could connect direct to the modem via PPPoE but the router couldn't. I flip/floped between them and consistently the router got the "concentrator" error when I pressed the connect button on 192.168.1.254, whereas my laptop worked everytime - browsed bbc.co.uk with no problem. I didn't reset the modem as I don't want DLM to kick in and drop my line speed even though fibre is meant to pick up speed quicker than ADSL.
I'll send the router back when it's received.
Thanks again.
GrahamClark
Dabbler
Posts: 21
Registered: ‎14-05-2013

Re: Router getting "Concentrator unreachable"

I received my new router on Tuesday 4/6/13 and decided to replace the old one - just in case.  Worked fine until about 18:00 5/6/13 last night when it failed to get a connection. powerin on/off the router did nothing. I connected my laptop to the modem via PPPoE and it worked. Reconnected the router and it still failed.  At about 19:50 the router connected OK and has since been working. Not sure what's going on here but I am a bit concerned by these connection issues via the router but I'm always OK when connecting my laptop. I might buy another brand of router.
Plusnet Alumni (retired) chrispurvey
Plusnet Alumni (retired)
Posts: 5,369
Fixes: 1
Registered: ‎13-07-2012

Re: Router getting "Concentrator unreachable"

I can see you lost sync at around 7.40pm on the 5th, but nothing happened with your connection at around 6pm.
Your laptop connection to the router, is that wired or wireless?
GrahamClark
Dabbler
Posts: 21
Registered: ‎14-05-2013

Re: Router getting "Concentrator unreachable"

Chris
I have 4 pc's connected via wireless and cable. I just happened to use a laptop to connect to the modem as it's more convenient to setup a wired Ethernet PPPoE as I can be next to the router.
When I noticed the line go down at 6pm I tried to use 192.168.1.254 to connect back to broadband with repeated failures. The modem had 3 green lights incl DSL.  At about 7:30 I decided to unplug the router and plug in my laptop to test it. This worked so I then reconnected the router and it didn't work.  I recycled the power on it a few times and eventually it picked up a connection. I have no idea why I should have lost sync as I didn't touch the modem I only removed the WAN cable from my router to the laptop and back again.
I can tell what time I loose a connection because the time on the router resets to year 2000, thus event log messages change to a new decade, presumably because it looses connection to your time server? Not sure why the router doesn't maintain the last known time?
GrahamClark
Dabbler
Posts: 21
Registered: ‎14-05-2013

Re: Router getting "Concentrator unreachable"

Actuallt it reset to 1st of Jan - not sure which year but I think it was 2000.
e.g. this is when I powered off the router.
Jun 5 20:48:46 IDS dos parser : tcp syn flood (1 of 1) : 192.168.1.64 23.62.53.99 0052 TCP 65485->80 [S.....] seq 2628724120 win 8192 

Info  Jun 5 19:13:57 SNTP Synchronised to server: 212.159.6.10

Error  Jun 5 19:13:57 SNTP Systemtime update: time setting 00:05:50 > new time setting: 19:13:57
Info  Jan 1 00:05:13 CONFIGURATION saved by TR69

Warning  Jan 1 00:04:36 DYNDNS Update failed for client dyndns_0 (Invalid hostname), host gandmalcrk.dyndns.org has not been updated
Community Gaffer
Community Gaffer
Posts: 5,275
Thanks: 599
Fixes: 5
Registered: ‎04-04-2007

Re: Router getting "Concentrator unreachable"

Ok, the session you have open with the exchange equipment is dying, but is still being held open until it times out.  The session uses the mac address of the router, so when you try and reconnect, it sees the stale session and uses it.  When you do a PPPoE connection it's a different mac address, so creates a new session.
We are currently investigating why it takes so long for this session to time out.  It should be less than a minute, but appears to be about 8.
We need to work out why you are disconnecting so often though.  That could be a fault.
Kelly Dorset
Broadband Service Manager
Plusnet Alumni (retired) chrispurvey
Plusnet Alumni (retired)
Posts: 5,369
Fixes: 1
Registered: ‎13-07-2012

Re: Router getting "Concentrator unreachable"

I'd suggest running through our faults troubleshooter at http://faults.plus.net and we'll take a look over your connection.
GrahamClark
Dabbler
Posts: 21
Registered: ‎14-05-2013

Re: Router getting "Concentrator unreachable"

I went through the faults app - a bit micky mouse but Ok for IT novices. It suggested that I had a faulty router or wiring - presumably because I can connect via PPPoE on my laptop.  This is my second router and the only wiring I use during testing is supplied by BT (modem cables ) and PlusNet (Ethernet cables ) The only thing I've never done since installation day is powered off the modem or disconnect it from the master socket. Rather not encourage a line speed drop!
I still may replace the router with my own.
If it happens again I'll attempt to capture more data. Let me know if you find anything.
Graham
 
Plusnet Alumni (retired) chrispurvey
Plusnet Alumni (retired)
Posts: 5,369
Fixes: 1
Registered: ‎13-07-2012

Re: Router getting "Concentrator unreachable"

Thanks Graham,
Our faults team will take a close look at your connection and update you with the results.
GrahamClark
Dabbler
Posts: 21
Registered: ‎14-05-2013

Re: Router getting "Concentrator unreachable"

More outages this morning. Not sure of the reason why as my wife was using the computer. She sais the internet wasn't working and she was being prompted for a username/password of some sort.
It is working now but the event log is interesting. You can see the router messages changing from Jan 1st to Jun 9th giving an idea of the time of outages. But the time stamps are strange - this is the order of events in the log. Is this an outage you are aware of?
Info  Jun 9 09:11:19 LOGIN User admin logged in on [HTTP] (from 192.168.1.11) 
Error  Jun 9 09:02:51 FIREWALL icmp check (1 of 1): Protocol: ICMP Src ip: 31.193.133.206 Dst ip: 80.229.169.48 Type: Destination Unreachable Code: Port Unreacheable
Info  Jun 9 07:38:15 SNTP Synchronised to server: 212.159.6.9
Error  Jun 9 07:38:15 SNTP Systemtime update: time setting 00:11:35 > new time setting: 07:38:15
Info  Jan 1 00:10:22 CONFIGURATION saved by TR69
Info  Jan 1 00:07:02 FIREWALL event (1 of 6): deleted rules
Warning  Jan 1 00:07:02 PPP link up (Internet) [80.229.169.48]  
Info  Jan 1 00:07:01 PPP CHAP Chap receive success : authentication ok
Info  Jan 1 00:07:01 PPP CHAP Receive challenge (rhost = ptn-ag04)  
Info  Jan 1 00:07:00 PPP CHAP Receive challenge (rhost = bras-red15.sl)
Warning  Jan 1 00:06:35 SNTP Unable to contact server: 198.18.1.110
Info  Jan 1 00:03:57 LOGIN User tried to login on [HTTP] (from 192.168.1.11)
Error  Jan 1 00:01:04 [ANTI_SPOOFD] (err) llist_getobject_at for ENV.ANTI_SPOOFD's value failed  
Warning  Jan 1 00:00:38 DHCS server up
Info  Jan 1 00:00:38 FIREWALL event (1 of 1): deleted rules
Info  Jan 1 00:00:38 FIREWALL level changed to Standard.
Error  Jan 1 00:00:36 UPnP framework enabled
Info  Jan 1 00:00:36 FIREWALL event (1 of 1): modified rules
Info  Jan 1 00:00:36 FIREWALL event (1 of 1): created rules
Error  Jan 1 00:00:30 UPnP framework disabled
Error  Jan 1 00:00:28 UPnP framework disabled
Error  Jan 1 00:00:26 UPnP framework disabled
Warning  Jan 1 00:00:14 KERNEL Warm restart
Info  Jun 9 08:24:48 LOGIN wireless station [2c:27:d7:4c:af:e2] can't get authorized.  
Info  Jun 9 08:14:48 LOGIN wireless station [2c:27:d7:4c:af:e2] can't get authorized.  
Info  Jun 9 06:55:44 SNTP Synchronised to server: 212.159.13.49
Error  Jun 9 06:55:44 SNTP Systemtime update: time setting 00:11:36 > new time setting: 06:55:44
Info  Jan 1 00:09:37 CONFIGURATION saved by TR69
Info  Jan 1 00:09:11 FIREWALL event (1 of 6): deleted rules
Warning  Jan 1 00:09:11 PPP link up (Internet) [80.229.169.48]  
Info  Jan 1 00:09:10 PPP CHAP Chap receive success : authentication ok
Info  Jan 1 00:09:09 PPP CHAP Receive challenge (rhost = ptn-ag02)
Info  Jan 1 00:09:08 PPP CHAP Receive challenge (rhost = bras-red15.sl)
Warning  Jan 1 00:06:35 SNTP Unable to contact server: 198.18.1.70
Error  Jan 1 00:01:05 [ANTI_SPOOFD] (err) llist_getobject_at for ENV.ANTI_SPOOFD's value failed  
Warning  Jan 1 00:00:38 DHCS server up
Info  Jan 1 00:00:38 FIREWALL event (1 of 1): deleted rules
Info  Jan 1 00:00:38 FIREWALL level changed to Standard.
Error  Jan 1 00:00:37 UPnP framework enabled
Info  Jan 1 00:00:37 FIREWALL event (1 of 1): modified rules
Info  Jan 1 00:00:36 FIREWALL event (1 of 1): created rules
Error  Jan 1 00:00:30 UPnP framework disabled
Error  Jan 1 00:00:28 UPnP framework disabled
Error  Jan 1 00:00:26 UPnP framework disabled
Warning  Jan 1 00:00:14  
jimbof
Grafter
Posts: 348
Thanks: 2
Registered: ‎02-05-2013

Re: Router getting "Concentrator unreachable"

At a hunch from looking at your logs; what seems to me to be happening is the router is crashing for some reason (see the "Kernel warm restart" message) and then after the router has restarted you are getting caught out by the 6-8 minute PPP timeout issue which Plusnet have - basically if you haven't cleanly disconnected your PPP session (which you won't have been able to do if the router has rebooted itself) then you can't connect to their access concentrator again for 6-8 minutes (exactly how long depends on exactly when the connection dies, as the keepalive is sent every two minutes, and it has to time out 3 times I believe).
If you google the "kernel warm restart" you'll see some people complaining about it on the O2 forums (I think they use the same router, different firmware).
GrahamClark
Dabbler
Posts: 21
Registered: ‎14-05-2013

Re: Router getting "Concentrator unreachable"

Thanks jimbof. It could be router firmware or a concentrator card in the exchange misbehaving or almost anything else. PlusNet are investigating this fir me.  This is my second TG582n router and it disconnects about 3 times a day on average. What I found strange was the time stamps - ignoring the Jan 1st stamps, some of the later event logs have earlier time stamps.
e,g,

Info  Jun 9 08:24:48 LOGIN wireless station [2c:27:d7:4c:af:e2] can't get authorized.
was an older log entry than
Info  Jun 9 07:38:15 SNTP Synchronised to server: 212.159.6.9
A bit weird but I guess it's something to do with GMT/BST switching.
I may well get a more advanced router in the hope it fixes the issue but I was hoping to wait until the price of 802.11ac routers come down.
Plusnet Alumni (retired) chrispurvey
Plusnet Alumni (retired)
Posts: 5,369
Fixes: 1
Registered: ‎13-07-2012

Re: Router getting "Concentrator unreachable"

I can see we've got an engineer appointment booked for tomorrow, let us know how it goes.