Various questions about the 7800N

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jez_uk1
Posts: 21
Joined: Tue Aug 16, 2011 7:50 pm

Various questions about the 7800N

Post by jez_uk1 » Tue Aug 16, 2011 8:10 pm

Hi all,

I've recently purchased a 7800N which I'm pleased with so far! A few questions I have:
I'm using an ISP in the UK connected via standard BT ADSL2+

Here's the information from the router:
DSP Firmware Version A2pB025f.d22k
DMT Status No Defect
Operational Mode ADSL2+
Upstream 446
Downstream 12552
SNR Margin(Upstream) 20.0
SNR Margin(Downstream) 12.3
Line Attenuation(Upstream) 11.2
Line Attenuation(Downstream) 21.0


1. I recently turned on PhyR, clicked on Apply and then Save Config (to the firmware). I used the Restart feature after that. When the router booted up it wouldn't sync up on the DSL at all. The DSL light was permanently off. On the web interface the DSP Firmware Version (on the ADSL status page) and the Hardware Version (on the advanced Status page) were both showing as unknown. I tried turning PhyR back off, no luck. I tried various restarts and even reloaded the firmware with the current settings - still no luck. It seemed the only way to fix the problem was to restore factory defaults. Strange indeed, perhaps a bug?

2. The system log is filled with messages like this:
daemon radvd[1392]: our AdvValidLifetime on br0 for 2a02:_____ doesn't agree with fe80::_____
daemon radvd[1392]: our AdvPreferredLifetime on br0 for 2a02:_____ doesn't agree with fe80::_____
Any way to stop these messages?
Is it possible to filter the system log to only show messages about the DSL connection?
Is it possible to see a report as to why the DSL resync'd during the night, what was the cause, etc?

3. How do I set the router domain name to "home" and the router's hostname to "gateway"? At the moment it's showing up as "gateway.home.gateway.home" which looks a bit strange

4. Is there any benefit turning PhyR on my connection? Does BT ADSL2+ support it? I have a relatively high SNR Ratio which might suggest noise on the line is a little variable. Is there any confirmation on the web interface that it's working?

5. How can I see which path mode the DSL is in? (FAST / INTERLEAVED)

6. Do you think I would benefit from setting the SNR margin manually? Do I need to restart the router when changing this value or it will resync automatically?

7. What is SRA in the ADSL Mode page (the Capability bit)? It's currently unticked

This is all that comes to mind, sorry for all the questions!

tinytim
Posts: 218
Joined: Sun Aug 14, 2011 4:53 pm
Location: Benfleet, Essex

Re: Various questions about the 7800N

Post by tinytim » Wed Aug 17, 2011 9:06 am

Well I might be able to answer some of these , but firstly I think your speeds are well down on what they should be. Have a visit to the BT speed test site at http://speedtester.bt.com/ and see what that says.

6. With BT's DLM I think that there's little point in adjusting the SRNM. Personally I'd look into why yours is so high first as BTs target is 6dB I think. With your attenuation a down speed of approaching 19meg should be achievable, along with an up speed of 1meg. Of course your ISP might be capping these figures.

7. SRA - Seamless Rate Adjustment meaning that the router doesn't need to resync to get a speed adjustment. This should probably be ticked.

You need to check out your internal wiring if you've not done so already. How are you connected up?

rossgrey
Posts: 12
Joined: Wed Aug 17, 2011 10:29 am

Re: Various questions about the 7800N

Post by rossgrey » Wed Aug 17, 2011 10:36 am

Another new user here - can answer one of the questions :)

5. The fast/interleaved can be determined by using telnet ( don't think its visable on the admin pages)

Using your telnet client of choice, logon to the router.
then type "adsl info --stats"

This will give a load of info , but at the top you will see something like ...

adsl: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 1060 Kbps, Downstream rate = 11296 Kbps
Channel: FAST, Upstream rate = 448 Kbps, Downstream rate = 8128 Kbps


Note the FAST after the Channel ...

HTH

jez_uk1
Posts: 21
Joined: Tue Aug 16, 2011 7:50 pm

Re: Various questions about the 7800N

Post by jez_uk1 » Wed Aug 17, 2011 2:45 pm

Thanks for these answers
firstly I think your speeds are well down on what they should be
I entirely agree. I have run the BT speedtester a few times for my ISP and they have passed this information to BT. Unfortunately the response from BT is that the line is functioning within the acceptable tolerances and that's where that line of enquiry comes to a grinding halt. My ISP is Idnet, they're an excellent service and I get good speeds for what the connection is synchronised at. I can't fault my provider and I know the problem is beyond their control.
You need to check out your internal wiring if you've not done so already. How are you connected up?
There is no internal wiring, the router is connected directly into the BT master socket (the socket behind the faceplate). I have tried various routers and microfilters. The setup in my appartment really is as simple as you can get. There's no telephone connected either at the moment. It's quite a new build development so I don't suspect the wiring to be faulty although anything is possible of course.

I only have two theories - 1. the "internal" wiring between my appartment and the BT DP on the ground floor runs in close proximity to some noise producing wiring, or 2. the problem is somewhere in the streets. Either way I'm on my own on this one sadly. I have to pay money to get a special faults investigation (I'm tempted, if only I know exactly what they can do about it).

Thanks also for the information about SRA and telnet, I'll check it out!

Edit: Information from telnet shows:

Code: Select all

adsl: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max:    Upstream rate = 22483 Kbps, Downstream rate = 14968 Kbps
Path:   0, Upstream rate = 446 Kbps, Downstream rate = 12552 Kbps

billion_fan
Posts: 4940
Joined: Tue Jul 19, 2011 4:30 pm

Re: Various questions about the 7800N

Post by billion_fan » Wed Aug 17, 2011 4:34 pm

Have you tried to lower the SNR using the hidden page

http://192.168.1.254/snr.html

I would suggest you try and set the SNR to 50 first and check the sync speeds for any chnage in speed.

If you do get a quicker speed you can keep lowering the SNR until you reach around 3db (with Be seems fine) and monitor the ADSL line, if your line becomes unstable keep raising the SNR until you achieve stability.

You might need to play around until you find the best SNR setting for you line

Hope this helps

Mad_Zoidberg
Posts: 2
Joined: Thu Sep 15, 2011 4:50 pm

Re: Various questions about the 7800N

Post by Mad_Zoidberg » Thu Sep 15, 2011 4:59 pm

Try an ADSL Nation faceplate on your master socket.

It's only about £12 on line.

I guess in a flat it's going to be a tough job to find out noise sources and eliminate.

As you say even the flat wiring might be a problem.

SNR setting of 50 is quite aggressive. I'd start at 75.

Just my 2p

DoomWolf
Posts: 6
Joined: Wed Jan 25, 2012 1:25 pm

Re: Various questions about the 7800N

Post by DoomWolf » Wed Jan 25, 2012 3:03 pm

jez_uk1 wrote:1. I recently turned on PhyR, clicked on Apply and then Save Config (to the firmware). I used the Restart feature after that. When the router booted up it wouldn't sync up on the DSL at all. The DSL light was permanently off. On the web interface the DSP Firmware Version (on the ADSL status page) and the Hardware Version (on the advanced Status page) were both showing as unknown. I tried turning PhyR back off, no luck. I tried various restarts and even reloaded the firmware with the current settings - still no luck. It seemed the only way to fix the problem was to restore factory defaults. Strange indeed, perhaps a bug?
Apologies for dragging up a thread from last August, but does anyone have an answer to this?

I ask because I got my 7800N on Monday and last night exactly the same happened to me as described above. I was worried that it may have been the ADSL modem inside the router dying as my old Netgear connected fine (my ISP is Be). I also found that restoring factory defaults was the only way to get the 7800N to reconnect, but restoring my previously saved configuration file would cause it to fail again.

It looks like I'll have to restore to factory defaults again and then re-setup my whole configuration from scratch, making sure to ignore the PhyR settings. :(

On the positive side, at least now I know it's unlikely to be a hardware problem and I won't have to go through the hassle of returning it Amazon.

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