Scenario:

- iPhone is set up so that it doesn't prompt you to join WiFi networks. (In other words, you're mostly depending on 3G when you leave the house.)

- You leave the house in the morning and you're on the road and you, let's say, wanna check traffic before you get on the freeway. So you unlock the phone screen and you punch up your bookmark to the traffic website.

- Most of the time, the above scenario works fine. But sometimes, about twice a week on average, you have the following problem:

- SPIN SPIN SPIN SPIN SPIN it never loads up the web site. It acts like theres no network.

- You look and it says FIVE BARS OF 3G.

- You wait some more. SPIN SPIN SPIN SPIN SPIN. Nothing.

- You try a different web site. Same thing. SPIN SPIN SPIN SPIN SPIN. Nothing.

- You put the thing into airplane mode and back into normal mode again, just to force it to disconnect and reconnect to the 3G network.

- You try again. SPIN SPIN SPIN SPIN SPIN. Nothing.

- You wait some more. SPIN SPIN SPIN SPIN SPIN. Nothing.

- You finally give up and power down the phone completely ("SLIDE TO POWER OFF").

- You power the phone on again and unlock its screen.

- Hit the bookmark to the website and BAM instant perfectly working connection.

The above steps make me think that the network stack on the iPhone is crashing in a way that isn't fixed by disconnecting and reconnecting from the network; only a full reboot fixes this particular crash.

Does anyone else get this? It's been happening on my 3G iPhone since I got it: Through a few different software updates and everything. I'd like to be certain that I'm not alone.

Can't say that I have seen this problem with the frequency that you describe. Maybe 3 or 4 times have I needed to fully restart the phone to restore connectivity, over the now 18 months I have had one.

I have mine set in a similar way, and it sits on WiFi at home and work. At home, I don't have e-mail access to my work push account. And every morning, the phone will have connected over 3G and grabbed my work e-mail during my 5 minute commute to the office.

In the past six months, I've seen this sort of behavior maybe four or five times.

In earlier firmware revs, the problem I'd have is that the iPhone would happily jump onto my home WiFi (using WPA2-Personal) but wouldn't jump onto our office WiFi (using 802.1x authentication with a custom config that I had to install). In the newest firmware release, that all seems to work now. Finally.

I'm also happy that I seem to have fewer web apps hanging and causing the watchdog to kill the browser. For all I know, Apple just made the watchdog timer wait longer.

I've also noticed fewer browser crashes. This seems to be separate from the browser, though. The problem seems to be specifically the 3G connectivity going Tango Uniform, because in these cases, connecting to a WiFi network allows for surfing as well as rebooting the phone does.

I have an Edge iPhone that does this and find it VERY annoying. I don't know if it's the same issue but I wish it would go away.

Stu

*bump*

I'm hoping Hugo sees this. :-)

The problem happened again this morning (scroll to the top to see problem description), and I noticed another characteristic that might be a factor. The problem still happens as I described it above, but here's a couple more data points.

- It always happens specifically when I'm leaving my house, i.e., It's dropping off of my home Wifi network and switching over to 3G.

- Just in case this is a factor: The Wifi base station (Actiontec GT701WG if I recall correctly) has had troubles with the iPhone in the past because the iPhone sometimes doesn't get proper DHCP/DNS resolutions from it. So I've long since set the iPhone to a fixed IP address and a fixed DNS address on my home network (I'm using the OpenDNS addresses), to work around that problem. So, when I run into the situation described above, it's when I moved from a Fixed-IP, Fixed-DNS Wifi network, to the 3G network.

- On mornings that it doesn't happen, I notice when I get into my car and pull out of the driveway it always says "3G" as I'm pulling out.

- On mornings that it does happen, I notice that when I get into my car and pull out of the driveway, it shows that I'm on my home Wifi network still, even as I pull out of the driveway and drive all the way down the street, well out of range of my home Wifi connection. Only after rounding the corner does it finally drop to 3G. And that's when I know the 3G will be non-functional.

- Today I just let it go without rebooting, drove all the way to work to be sure I was on a different cell tower, and tried using the internet again. Same problem: 3G data just does. not. work. until I reboot the phone, then it works fine. So I know it's not specific to the cell tower.

I think there's some kind of a bug in the code that pops up only on a Wifi->3G handoff, and I wonder if the fixed IP and fixed DNS has anything to do with it. Such as (wild guess example): if the Wifi drops in the middle of a DNS request, and it doesn't go through the DHCP code because Wifi is on a fixed address, then the DNS client "sticks" on the Wifi connection and can't switch back over to 3G. Or something really silly and esoteric like that.

What I find interesting is that Airplane mode on and off does not fix the problem, yet rebooting the phone fixes the problem. I don't know about the internal architecture of the network stack, so I'm hoping Hugo can see this and might know: What bits of the network stack don't restart when Airplane mode is toggled? What bits of the network stack can only be restarted by a full reboot?

To rule out a DNS problem, make a network connection to an IP address instead of a hostname. For example.

Good idea. I actually thought of that, too, as I was typing that post above. The next time it happens, I'll do that.

*makes shortcut now*

http://developer.apple.com/bugreporter/

You can use that with a free iPhone developer account. The few I have submitted over the years for OS X usually get decent responses, so it's not going into a black hole.

Yeah, that's about all I can recommend too. The wifi/cell radio are really pretty separate (those with hacked phones can run ifconfig and see) so there is no specific "handoff". Obviously there is some magic at a higher level which decides a network interface has gone away and anything outstanding needs to be retried on the remaining interface... but that's about all I know about the matter

Hugo

Thanks so much, Hugo!

Does anyone think I've collected enough information to submit a bug report? If it happens again, I'll try the direct-IP-address thing, but beyond that, I don't know what else to do, diagnostics-wise.

You could switch back to DHCP.