AMB Laboratories DIY Audio

[mawi]

If I browse the forums from my mobile I quite often get time outs after browsing a few pages. If I try using my desktop browser after these timeouts they also don't work. Access usually works again after a few minutes. It seems that either the forum goes down or is getting blocked, perhaps due to the mobile browser misbehaving. If there anything server side that could be causing this?

[amb]

It's probably not a problem with the server or I'd be hearing a lot more about this. Maybe you're getting poor mobile data reception? Network congestion? Do you see this problem on all types of connections (3G/4G, Wi-fi, DSL/cable)?

On your desktop computer, you can check the number of network hops to the amb.org server and the amount of time spent on each of them. Maybe that would be telltale. On Linux/Unix and MacOS X, open a terminal window and type the command:
traceroute amb.org

Make sure that the traceroute command is in your PATH environment. On some systems you need to be logged in as root to use this command. On Windows it's the same except the name of the program is tracert

Btw, I recommend that you install the Tapatalk app on your mobile device (if it's a supported platform). It makes the forum a lot more user-friendly on a small mobile screen. See this thread for more info.

[mawi]

I've done some further diagnostics and am able to reproduce 100% of the time. If I browse from my mobile device (Android phone running Chrome Beta) it'll timeout after 3 or 4 pages. I am then not able to access amb.org from my desktop (wired all the way to the router) or laptop (wireless) for ~10 minutes.

mtr shows the following last few hops, and is the same for both when the site is okay for me and when it's not:

Host                                        Loss%   Snt   Last   Avg  Best  Wrst StDev1
22. 4.69.140.145                      0.0%     6  150.9 150.8 150.7 150.9   0.1
23. 4.69.133.149                      0.0%     6  150.7 151.0 150.6 151.3   0.3
24. 63.211.150.26                     0.0%     6  164.0 179.1 164.0 253.6  36.5
25. ???

When I cannot access the site I can see SYN packets leave my border router from browser requests and if I try to start a session from the firewall using nc to port 80. I do not see a returning SYN ACK. The conntrack table doesn't show any established connections to 69.17.54.104, just a bunch of time waits and the SYNs that aren't getting a reply. Tapatalk doesn't work on the AMB forums either during this time and I can browse other sites just fine. If I drop and re-initiate my PPPOE interface, which gets me a new IP address, I can browse the site again after 30 seconds or so.

When I can access the site, the SYN ACK comes back around the 200ms mark, in line with what the traceroute is saying.

It's as if my IP is getting blocking IP due to something the mobile browser is doing.

I'll do some packet dumps of the mobile browser traffic tomorrow and see if that shows anything interesting.

[amb]

Weird. Have you tried using Tapatalk? If so does it also cause the same problem?
It would also be interesting to test your android on someone else's wi-fi network, or via 3G/4G, to see if it's an interaction that's localized to your ISP.

[mawi]

Tapatalk works fine. Browsing with the Android Chrome browser over 3G is also fine but my provider has a proxy which is transcodes images and may change the session in other ways. Trying via another wireless connection and I get time outs. I'm unable to confirm the source IP is blocked as I only have my phone on that WLAN but the symptoms from the phone are the same.

I've taken a package capture this even and the last few requests are as follows:

GET /apple-touch-icon-precomposed.png HTTP/1.1
HTTP/1.1 404 Not Found
GET /apple-touch-icon.png HTTP/1.1
HTTP/1.1 404 Not Found
GET /apple-touch-icon.png HTTP/1.1
HTTP/1.1 404 Not Found
GET /apple-touch-icon-precomposed.png HTTP/1.1
(no reply after this and connection completes the closing 4 way handshake after a few more seconds).

There are quite a lot of retransmissions and duplicate ACKs towards the end of the session.

On one hand, I've solved my problem - I'll use tapatalk. It's a really nice interface. One the other I'm intrigued as to why this problem is happening. Weird indeed!

[maladat]

I realize this is an old thread, but I figured I would reply here after finding this page doing a Google search on the same problem.

Using a stock HTC One X running ICS on AT&T service I can also view 3-4 amb.org pages (both forum and main info pages) before new pages simply don't load. This happens whether I am connected to the internet on my phone using 3G, LTE, or WiFi. As the previous poster wrote, after about 10 minutes I can view another few pages before new pages won't load again. This happens using several different browsers on my phone, and if I have gotten into the no-response period with any one browser, none of the others will load pages, either.

If I am NOT in one of the no-response periods, I can use Tapatalk on my phone to view the forum with no problems.

If I am NOT in one of the no-response periods, I can tether a computer to my phone's internet via WiFi or USB and view all amb.org pages with no problems.

If I AM in one of the no-response periods, Tapatalk on my phone will not load the forum and a computer tethered to my phone's internet will not load any amb.org pages (until the 10 minutes following the several page loads passes).

Further, if my phone is getting internet through a WiFi network (for instance, my home network), and I load several pages until new pages stop loading, no other computers on the network will load any amb.org pages until the no-response period runs out.

My conclusion is that something is wonky in how my phone is requesting pages that is either causing your server to flag its IP address as a problem and not respond for 10 minutes (which would cause the network issues since my phone and all the computers would appear as the router's IP address) or that somehow responses to its IP address are just getting plugged up somewhere.

As further evidence to support my IP Address/Web Server theory, if I turn off WiFi on my phone such that my phone is using its cellular data connection (and thus has its own IP address) and load pages until they stop loading, then immediately switch on WiFi and connect to my home network (such that, for internet requests, my phone now appears to have my router's IP address) I can immediately load a second round of a few pages.

[amb]

If this occurred at around US/Pacific time around midnight last night, lasting about 2-3 hours, the amb.org server and several other internal machines were performing online software updates which swamped our network bandwidth. I hope the situation has resolved itself.