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Author Topic: Static IP config in iOS 10  (Read 2875 times)

Weaver

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Re: Static IP config in iOS 10
« Reply #15 on: March 29, 2017, 10:04:39 AM »

Can't reproduce this on Mrs Weaver's iPad 6, ios 10.2.1 either, and hers is a 64-bit box the same as mine, only difference is that this is an iPad Pro. And there is now a dhcp server present on the Lan, which was not the case the other day. But that is insane.
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Weaver

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Re: Static IP config in iOS 10
« Reply #16 on: March 29, 2017, 11:04:45 AM »

Upgraded this box to iOS 10.3 to see if that would help. Same problem even after upgrade and of course a cold boot, so even a reboot did not clear it.

But now I have fixed it. I managed to work around the bug. I did a 'forget network' and then the problem was cured, for how long I don't know. I suggested to Apple that I think it would be a good idea to report this as a bug. It is definitely state-dependent, and we know it can be cured by deleting a data structure.

It could be some corruption of the database of wireless Lan settings, or else some related data structure. The machine can not possibly be running low on RAM as no other processes were running on one occasion. Unfortunately I have no idea how to get it into this state, but once it is broken it remains so forever so it seems. It failed in this way dozens of times over several days. Also since I had just cold-booted the o/s, it is not due to corruption long-term, and it has to be something messed up that can survive in _persistent_ storage and continue to cause trouble even after a reboot.

It is going to be a nightmare for Apple to reproduce. The question for developers is, what could cause the machine to reject settings or throw an error so they are not retained when you enter them in the static ip page. The exact values entered seem to be irrelevant, I tried various different values on two different machines. An example that is known to fail (amongst many others) is IPv4 = 192.168.1.22 netmask = 255.255.0.0 and no other values entered. It still fails if other values are given as well e.g. Default gateway and dns server. It fails if different netmasks are used and also fails with 10.0.0.0 netmask 0.0.0.0 for example.

There are three entries showing in the list of wireless lans, only one of them has a saved password and other settings associated with it. I did not try repeating the test with a different wireless Lan, and in any case it wouldn't have been an ideal test as it would have meant entering a password and presumably creating data structures from scratch anyway.
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sevenlayermuddle

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Re: Static IP config in iOS 10
« Reply #17 on: March 29, 2017, 01:17:07 PM »

Glad to hear the work-around did the trick.

Just guessing, but I wonder if the pattern of behaviour depends upon whether a DHCP lease timer is running when the change from DHCP to static is made?
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Weaver

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Re: Static IP config in iOS 10
« Reply #18 on: March 29, 2017, 02:08:09 PM »

I'm not sure I understand the implication of the question.

Yes there is a DHCP lease running on that interface. It's so weird that I could not reproduce this on another iPad with the exact same o/s, same processor and same wlan. There has to be some way of getting it into this screwed up state. And once it's in it then you've had it until you delete something that has become screwy.
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sevenlayermuddle

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Re: Static IP config in iOS 10
« Reply #19 on: March 29, 2017, 02:37:42 PM »

I'm not sure I understand the implication of the question.

No particular implication, just trying to speculate about why it happens sometimes and not others.
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Weaver

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Re: Static IP config in iOS 10
« Reply #20 on: March 29, 2017, 08:17:23 PM »

No, I wasn't thinking straight because as it happens. There would have been a DHCP lease timer in progress in every case, even in the case where it worked on another machine. I never thought t9 bring the interface down first and then turn off the dhcp server before trying the UI test, for the sake of science purely.

It has to be a completely mad bug on their behalf does it not? I am actually wondering if it does something like throwing an expection when it exits and scans or commits the contents of the static ip settings dialog box (or whatever the correct Term is in the iOS GUI). That would explain in part why it is as if you never made any settings changes at all. I'm also wondering if it could develop a dislike for blank fields under certain mad buggy circumstances although I did also try unnecessarily filling in default gateway and dns server fields with plausible junk just to see if that would pacify it.
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sevenlayermuddle

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Re: Static IP config in iOS 10
« Reply #21 on: March 29, 2017, 11:24:18 PM »

Just speculating, but...

Typically, an iOS App would save config data to a local memory object.   In response to various events, such as when something changes, or the App enters background, that object is written to filestore.   When the App next launches, or just when the App thinks fit, the object would be restored from file, replacing the object in memory.

When a setting 'vanishes', it suggests to me that there is a loophole in the App, such that the object containing the data is not written to file when it should be.   The App logic failed to realise it needed writing, or maybe restored it from file without having ever saved it.

Simply an ordinary software bug, the likes of which kept me in a job when I worked for a living, and provided for my pension. :)
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Weaver

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Re: Static IP config in iOS 10
« Reply #22 on: March 29, 2017, 11:53:16 PM »

Good point. I've seen the analog of bugs like that, although I haven't done too much application code, usually lower-level components. I have asked them politely to report it and they now have a couple of emails with very detailed bug reports establishing some of the boundaries, not that I can help too much.

Anyone else with an iOS device could just give it a quick try if they want to contribute, decent test values are ip = 10.0.0.0 netmask 0.0.0.0 and nothing else filled in, or else 192.168.1.22 netmask 255.255.0.0 as it failed on those and many others
« Last Edit: March 29, 2017, 11:57:15 PM by Weaver »
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sevenlayermuddle

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Re: Static IP config in iOS 10
« Reply #23 on: March 30, 2017, 12:08:25 AM »

It seems to be quite a commonly recognised issue, mentioned on various forums when I searched.  That (these forum threads) are what inspired me to suggest 'forget this network'.

Don't hold your breath waiting for Apple to fix it, or even to seriously investigate.   I hold Apple in high esteem as regards general software quality, but obviously all sofware has bugs and unless it is a security-critical issue, Apple are no better than any other at admitting to the bugs and fixing them.

The most common answer I found to your issue on Apple forums was to configure a fIxed IP on the router, rather than a static IP on the device.  You and I know that is ridiculous and irrelevant, but it is accepted by most morons.
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Weaver

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Re: Static IP config in iO
« Reply #24 on: March 30, 2017, 02:26:43 AM »

I didn't realise that this was a known thing. Doesn't say much for Apple tech support who acted as if they had never heard if it, or genuinely never had.
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d2d4j

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Re: Static IP config in iOS 10
« Reply #25 on: March 30, 2017, 08:34:21 AM »

Hi weaver and 7lm

I just manually set my iPhone 5, iOS10.2 to weavers suggested 10.0.0.2 and 255.255.255.0 only, which it accepted and saved (stopped/turned on  wifi after change to make sure it had saved setting)

No internet connection was available to the mobile, and the mobile did not revert to 4g, as it believed it was connected to wifi

Setting it back to dhcp, stopping wifi and restarting wifi again brought my correct settings back as the router set, including 3 IPv6 addresses

Many thanks

John
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Weaver

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Re: Static IP config in iOS 10
« Reply #26 on: March 30, 2017, 10:04:47 AM »

I have no idea how to get it into this bad state, as I may have said before. But I have noticed, as 7lm pointed out, that there have been a few reports of other people having seen this.
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d2d4j

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Re: Static IP config in iOS 10
« Reply #27 on: March 30, 2017, 11:03:09 AM »

Hi weaver

It may be unique to iPad which I do not have latest iPad, only iPad we have is on ios9

Many thanks

John
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sevenlayermuddle

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Re: Static IP config in iOS 10
« Reply #28 on: March 30, 2017, 11:55:52 AM »

I have tried on a couple of iOS 9 iPads, couldn't reproduce it.

Btw.. In fairness to Apple, the fact a few folks have moaned about it on a few forums doesn't mean they've actually reported it to Apple as a bug.   Weaver has done the right thing by reporting it, but have the others?

And if people don't tell Apple, Apple are unlikely to prioritise a fix.
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d2d4j

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Re: Static IP config in iOS 10
« Reply #29 on: March 30, 2017, 12:06:12 PM »

Hi 7lm

Your correct

Also, I would think the vast majority just use dhcp, which we do, but we have our dhcp assign as we need and static assign using MAC address, so it uses correct vlans for the devices

Also, I seem to remember Apple had an issue on iOS5 or 6 I think, where a lot could not connect to wifi, due to Apple adhering to tightly in the network protocols where as most routers etc were more relaxed and the iphone would not connect unless it matched the same standard

Please accept my apologies if I have not remembered correctly and Apple very quickly fixed it

Many thanks

John
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