Need help for tracking down cause of intermittent network outages

[Surreysteve]

Hi Guys

Just joined this excellent looking group and hopeful I have at last found a helpful forum that covers my rather complicated and growing Home Network. I am also hoping I am posting this in the right place as it covers a number of different topics - but posting individual discrete questions didn't seem to make much sense when I'm looking for some holistic advice.

All help and advice on the following would be welcomed. I will of course read through the existing forum posts and see what I can glean.

I have a network with a main ADSL Router (Netgear D6400) hard wired to 6 network points. I then use 4 Netgear DGND4000 as wireless access points (DHCP disabled) together with a couple of switches. The house is fairly large (WiFI unfriendly) and we have 3-4 media files servers, 2 games consoles, 4-5 PCs and around 6 Smart TVs plus usual Smartphones/IPads etc (4-6 concurrent). I guess a reasonably typical home network for 6 people and visitors all of whom are pretty active with Smartphones, PCs, games etc etc The D6400 is operated with wireless disabled as it sits in the loft amidst considerable radio interference. It was purchased (in ignorance I guess) as a suitable powerful main router!

We have a standard (non Infinity) BT ADSL connection which gives 16m down and 1m up.

The system chugs along reasonably OK but around once/twice a week we have problems when the network suddenly slows right down and even with everyone "hands off" on the network the ping goes up to 1500-2000ms (from 20ms) and the up/down bandwidth reduces to around 10% of its normal value. This affects all PC users on the Network and not just a single PC. There never appears to be any obvious cause for the issues but a reset (or power cycle) of the main router nearly always returns normality.

I have looked at Wireshark and Glasswire but these utilities just monitor the Network traffic on the machine on which they are run, rather than giving a holistic picture of what is going on across the whole network of 20-30 nodes.

My suspicions as to what is going on are some or all of the following: Rogues device consuming bandwidth, Network storm? or some weird handshaking between the routers when they are exchanging information eg DHCP, routing tables etc etc

There does not appear to be much facility on the D6400 to look at bandwidth by IP address(device) or to save central logs of network traffic for analysis. Is this the case or am I missing something? Can QoS be used somehow? Is there a logging facility that I am missing?

Assuming not much functionality is available on the D6400 - what would anyone recommend? I read that some people switch to DD-WRT to gain better functionality? Or maybe, is there a more sophisticated router I could use to achieve a more manageable setup ie one where I could do some level of debug/analysis rather than just switch things on/off to solve issues? I have been told by one person that the D6400 may not be up to the job.

I am more than happy to invest in different kit to achieve a superior network and one that gives me some future proofing for NAS streaming and especially any forthcoming cable/BT Infinity rollout when my available bandwidth would increase. My ideal would be a "bomb proof" network with a far greater level of monitoring/debugging/logging ability enabling some management other than just power cycling the main router when problems occur. I am more than happy to have the main router as a separate modem/router and it does NOT need WiFi

Apologies for the long post - all help and advice welcomed?

 

[thiggins]

A simple step would be to install a smart / managed switch and move all LAN connections to it. This would give you the ability to see traffic by port, which should quickly point to any machine consuming large amounts of bandwidth.

You might also use Fing to perform a scan of all devices on your network to check for devices you didn't know are there.

I assume you've checked the router's log to see if anything is flagged during the outages. Make sure you have all logging options enabled.

 

[CaptainSTX]

To solve problems such as yours you need to begin eliminating possibilities.

One thing to eliminate is AC power issues. Plugging your modem, router and as many other network devices into a UPS(s) will eliminate power glitches as the possible source of network problems and even if power turns out to not be the source of your current problem you end up with a more "bomb proof network" which is what you are seeking.

 

[Surreysteve]

Cheers Tim.

I may be being dim here, but the D6400 does not appear to keep any logs. It has some pretty basic QoS stuff and the ability to monitor total bandwidth. Am I missing something?

I do like the suggestion for a smart/managed switch - Any you'd recommend? ....especially do Netgear do a decent one (seeing as rest of my kit is Netgear)

 

[ColinTaylor]

As an ex-ADSL user my first suspect would be noise on the telephone line. ADSL is extremely dependent on a clean line, if there is any sort of noise the modem will re-sync at progressively slower speeds until it can maintain the connection.

Intermittent speed problems like you describe are very common with ADSL unless you're sitting right next to the telephone exchange.

To check whether this is your problem log onto the D6400 and go to ADVANCED > ADVANCED Home. Then click the Show Statistics button.

Under ADSL Link look at the Connection Speed. Make a note of it. The next time you have the problem check the speed again and see if its gone down.

http://www.downloads.netgear.com/files/GDC/D6400/D6400_UM_EN.pdf

 

[sfx2000]

I do like the suggestion for a smart/managed switch - Any you'd recommend? ....especially do Netgear do a decent one (seeing as rest of my kit is Netgear)

Netgear's GS108 series are quite good for the price... there are different models that have specific feature sets...

 

[thiggins]

I may be being dim here, but the D6400 does not appear to keep any logs. It has some pretty basic QoS stuff and the ability to monitor total bandwidth. Am I missing something?

I'm not familiar with the D6400. If you can't find a log, it probably isn't there.

I do like the suggestion for a smart/managed switch - Any you'd recommend? ....especially do Netgear do a decent one (seeing as rest of my kit is Netgear)

As SFX suggested, the GS108 is fine if you're comfortable with NETGEAR.

 

[ColinTaylor]

According to the manual the logs are at: ADVANCED > Administration > Logs