Network Engineer Stumped and Requires Brain-Power Assistance! :(

N

Nunnsby

New Member
Joined
Apr 10, 2012
Messages
5
Reaction score
0
Location
Bryanston, JHB
Background: Live in Bryanston, JHB. Senior Cisco Network Engineer for 15 years. Know Routing and Switching and Wireless. This is what I do for a living.

I have recently been moved to a nice, new, shiny MSAN - which has actually already been graffiti lol - and am now on 4Mbps Telkom ADSL. Yes, I can go to 25Mbps, but 4Mbps is fine for me for now.

Couple of things:

1) Using both the Telkom Guest Account and an Afrihost 1GB Free account I see I only get 2Mbps a sec download on Speedtest sites, yet my router is telling me I am getting a 4Mpbs signal from the MSAN. Issue number 1.

2) This is where it gets really weird ...

The scenario:
Wireless Router - TrendNet
I have the following devices:
* MediaCentre PC, Windows 7
* XBox 360
* Normal PC with Windows 7
* iPad
* HTC Mobile Phone, running Android
* RaspberryPi running Raspbian
* Work Laptop running Windows 7

Everything connects via Wireless, except the RaspberryPi. This is a direct LAN Connection.

Up until I was put on the MSAN, EVERYTHING WORKED FINE!! EVERYTHING!!! XBox 360, at the same time as downloading Torrents AND NZB's from News Server, and surfing the web ... etc etc etc

Now ... ONLY the Work Laptop works fine. Everything else that connects to the Wireless, or the LAN, IS NO LONGER WORKING FINE. RaspberryPi can look for updates and potentially do small files, but the minute it hits a big file, anything over a few KB's, it breaks and sits there doing nothing.

The other devices can connect to the Wireless, and can ping the world fine, but cannot connect to the internet, in general (browse). None of the sites load. But, I can ping any site no worries. I can FTP to a site fine. I can even connect to BING and do a search. But the minute I click on a full featured site, or a result .... Broken. Nothing. Never loads. Says it is "waiting for ... (the site)"

So, one would think DNS! As I mentioned, DNS working fine. Can ping everything. NSLOOKUP Works fine. I can telnet news.is.co.za on 119 and get the IS disclaimer, so ... "working fine" ... but can't "connect" to it or pull files from any other machine. Other than the Laptop, which is working fine, for everything.

The Laptop, works 100%. To the point I can watch YouTube, listen to Soundcloud, download large FTP and HTTP files and NZB from IS News and Torrrent. But on the Media Centre, et al ... Nada.

Xbox won't connect. Phone, iPad, nothing. Turn off Wireless and put it on 3G and it works fine. So it is not a browser issue on any of the devices.

Round about now you're thinking Driver on PC or something ....

Weirdest thing ... I fire up a BitTorrent on the Media PC, where nothing is working, no News, not Browser, not Anti-Virus updates, only thing that loads is Bing and newshost.co.za - text-based site ... as mentioned, fire up BitTorrent .... and it runs at full speed! 2Mbps down - remember I'm only getting 2Mbps currently! But, it shows Bittorrent is running 100% on the Media PC, which means ... connectivity and the Internet is there! Wireless LAN file transfers run at full speed as well between LAN PC's, so it is NOT the Wireless either.

I would obviously assume I'm being shaped ... it's happened before ... but this ... this is weird. If I was being shaped ... it would be an overall experience ... but here, Laptop working at the speed of 2Mbps DSL for everything. BT on the MediaCentre at 2Mbps, but any other site/service on any other device else does not work. DNS and Ping and text only sites, yes, which points at Shaping, but why does the Laptop run at full speed and my BT's on the MediaCentre as well. News doesn't work at all on the MediaCentre PC, but runs fine on the the Laptop.

Maybe it is Malware ... possibly, but why is the Phone and iPad and RaspberryPi not working then. Those are Not Windows Machines.

Ahhh, okay, it must be the Router ... maybe it a firewall rule? Nope, nothing there. Also, Set the Laptop to DHCP or Static and it works fine. Doesn't matter what the IP or Range is ... it always works fine.

Maybe the router is Poked or requires a Firmware upgrade to work with the MSAN ??? Swapped it out for a Cisco with ADSL. That does exactly the same thing. I have a free 1Mbps Afrihost account ... tried that ... same thing. On both routers. Even the Telkom Guest Account to connect to Telkom and the SAIX Speedtest site ... same thing. Only works on the Laptop. Nothing elseworks. I'm using OpenWeb as my ISP currently.

So the only thing I can think of is that I'm being very intelligently throttled ... could Telkom/OpenWeb/IS be "watching" the line to see what agent on what device is talking, and is only allowing one at a time. Or even only one, the Laptop? Is this even possible, cause there honestly is no other explanation.

Any thoughts?
 
1. post router stats
2. Have you tried using another DNS like google? 8.8.8.8 and 8.8.4.4
3. Afrihost's capped accounts aren't speed limited.
4. Web Africa also have a free 2gig account you could try.

5. My gut says you aren't actually syncing at 4meg. You're probably syncing at 2Meg.
 
Not sure about the specifics but the people that knows would be able to expand. I have the same issues, when I switch on my ADSL router I lose network and Internet connectivity for my wireless devices. It's got something to do with the stack order or stack priorities for the network I guess but I did not yet have the will to dig deeper to find the problem. At the moment I use Afrihost MTN mobile data due to Telkom issues on my side but hope to return soon to ADSL.

There was a similar thread with posts where someone mentioned a way to resolve it but for the hell of me I cannot find it.
 
Last edited:
I'd try lower the MTU on one of the problematic devices / router and see if the problem goes away.
 
I have had the same experience with line speeds. Our exchange was till recently only 4Mbps capable but if I only subscribed to 4M and it synced to 4M I was lucky to get 3M out. Same line same ISP I was subscribed to 10M service for years modem would sync at around 6M and that was the throughput I got.

Now since the upgrade, only 10M capable =( *huff* but now it syncs at 10 M and I am overjoyed to be getting 8.7M from the speed tests =)

I thought this was normal what more can you expect?
 
I would check the router. It seems the obvious starting point. Check your line attenuation and SNR levels. Maybe borrow an VDSL router and see if it plays nice with your new MSAN? You could also ask Telkom or your ISP is there is an exchange problem/congestion in your area.

Secondly I would test the wireless. How cluttered is the frequency you are using?
 
Last edited:
Just a few things to set aside first (since you are very clued up so just a reminder)
1. Have you checked if there is another router serving DHCP on your network?
2. Any of your computers setup with ICS?
3. Have you tried using 8.8.8.8 as DNS?

My diagnostic ideas

1. When you can torrent on your HTPC but not access internet properly, it sounds very possibly that its a DNS problem, being able to ping a server doesn't necessarily mean the server is actually at the IP address served, an outdated DNS server sometimes serves incorrect addresses. Best way will be to ping the address on your working computer and try accessing that site with the IP.
2. Are you maybe doing MAC address filtering on your router? If you're able to download a few small files but nothing slightly bigger it might point to this.
3. Check the IP address of your working computer, take that comp off the network and give the IP to another device to see if that works? if the second point above is true, you should also try changing MAC address in Windows Reg and try your HTPC.

Just my 10 cents worth.
 
To see if it's a DNS issue do a nslookup from one of the devices that is not working. Did you save a DNS server somewhere on the router or are you using auto DNS config from ISP?

c:\>nslookup
Default Server: Server1.local
Address: 10.1.200.20

> google.co.za
Server: Server1.local
Address: 10.1.200.20

Non-authoritative answer:
Name: google.co.za
Addresses: 2c0f:fb50:4002:800::101f
74.125.233.63
74.125.233.55
74.125.233.56

If you don't get any info then it's DNS issue
 
Today said:
I'd try lower the MTU on one of the problematic devices / router and see if the problem goes away.
Click to expand...

This sounds like a reasonable possibility. To add to the other troubleshooting, I'd suggest testing between devices on your local network too. For example, can you download a large file from the Pi, using one of the devices hooked up via wireless?
 
Yep - I would also say MTU. Do you have issues with SSL enabled web sites too?

What router do you use? For a Cisco you can use ip tcp adjust-mms on the dialer. I adjust to 1440 with rather good success. Mikrotik should by default add rules in the firewall to adjust (if enabled), and I'm not sure about other routers.
 
Hey all

Thanks for all the great ideas and assistance. I got home after work late last night to find ... everything working 100%. Checked the Router uptime is over a day, so it hasn't been rebooted, and no one has made any changes to it since I posted this message, when NOTHING was working except the laptop.

I'm hoping it is still the same when I get home this evening!

In the meantime, thanks for all your help and assistance and suggestions and time, and if the network has a relapse, I'll drop a message in here again for assistance.

Regards
 
You must log in or register to reply here.
Back
Top
Sign up to the MyBroadband newsletter
X