Self-Assigned IP Address

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I have spent several years researching this and trying everything I have found.

The only thing that ever worked for me is setting the IP address manually.

Keep in mind that when I visit this place I only have an iPad and an iPhone. I don't have a laptop. So, the solutions that involve stuff like Network Diagnostics and deleting configuration and/or preferences files doesn't apply.

However, I may have a clue:

All the SSIDs of the places I visit (and my own SSIDs) are in my iCloud Keychain, except for this one place (classkorat) which is not in the iCloud Keychain but is in both the Login and System keychains. No idea how this happened or why it happened.

Screenshot 2019-09-07 06.27.21.jpg

Screenshot 2019-09-07 06.28.11.jpg

I will delete these SSIDs from. Next time I visit they should be added to the iCloud Keychain. That might work.

We'll see. Unfortunately, I probably won't visit this place soon as I will be away from home for the next few weeks.

Stay tuned.

Screenshot 2019-09-07 06.27.21.jpg
 
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I occasionally have this problem at hotels where I can't connect to their WiFi

Have you tried this:

From the menu bar, select
 ▹ System Preferences... ▹ Network ▹ Advanced... ▹ DNS
Under DNS Servers you should have one or more numerical addresses, such as “192.168.1.1” or “10.0.0.1”.
Delete those addresses, then, in the TCP/IP tab, click Renew DHCP Lease.
Close the preference pane and save the changes.
Try the sign-in procedure again.
 
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Thanks for the suggestion @krs. I'm on a iPhone/iPad. But, yeah, I have tried with no DNS, Google DNS, Open DNS, etc. No joy in this particular situation. It is worth remembering, though.

Here's the only thing that has worked for me:

  • Configure IP: Manual
  • Enter an IP address that I think will work
  • Enter a Subnet Mask appropriate for the above IP address
  • Enter the router IP
  • Configure DNS: Automatic

After doing that it connects immediately and I'm good to go.

The way I get the IP address I think will work is by asking other customers what their IP address is. From that make up a useable IP and I can deduce the Subnet Mask and router IP.

So, it's pretty clear that this is a DHCP problem. For some reason, their router won't give either of my devices an IP address, but it will give an IP address to everybody else.

Another thing to note: This particular chain of coffee shops uses the same SSID and password at every location. I have no trouble connecting to the WiFi at other branches, it's just the one closest to my house that doesn't work.
 
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There has to be something in your settings that is not working with the router set up. Your workaround will work until the router issues a number to someone that is the same as the manual number you have entered. At that point both you and the other user will start getting errors about networking issues. Does DHCP work for you everywhere else but this one shop? And only on the iPhone and not the iPad? Just want to make sure about what is happening before making any suggestions.
 
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There has to be something in your settings that is not working with the router set up. Your workaround will work until the router issues a number to someone that is the same as the manual number you have entered. At that point both you and the other user will start getting errors about networking issues. Does DHCP work for you everywhere else but this one shop? And only on the iPhone and not the iPad? Just want to make sure about what is happening before making any suggestions.

So far I’ve never had the problem of picking an IP address that’s already in use or that gets assigned after I start using it.

DHCP works everywhere else. It only fails at this one shop.

The problem affects both my iPhone and iPad. It continued to affect my iPhone even after I did a complete reset of the device in order to leave the iOS beta program.

I have tried forgetting the network and resetting network settings on both devices.

The big problem with the workaround is that this chain uses the same SSID and password at all branches, but different subnets. If I go to a different branch I assign myself an IP address in the wrong subnet. So, I switch to automatic DHCP which works fine until I return to the problematic router. (ZTE brand, BTW.)
 
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Did you try switching to the wrong subnet at this location? Try to connect, then switch back to DHCP?
 
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Just thinking out loud, but given that all of the shops use the same SSID and password, do they all use the same network addresses? That is, do they all use 192.168.x.y? If not, and if your system has the SSID/login information stored for a different shop, maybe when you enter this one it tries to use that data and cannot find the router. That's a stretch, but could explain why others can get in and use the network and you cannot.

I know you said you tried "forgetting" the network, but it may be that some artifact is still hanging around. Also, I noted that classkorat apparently has two separate networks, one not showing the band and one for 5Ghz. Do all of the shops separate their bands by name like that?

You might also look at a network analyzer application, something like "Fing," or "Network Analyzer," to try out in the shop to see what is actually being broadcast by the router. Just go to the App Store and search for "Network Analyzer" and there are lots of options.
 
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I’ve used both Fing and Net Analyzer to look at this network. Nothing stands out.

Both of my devices are able to find the router and log in with saved passwords. But, DHCP fails for both. As soon as I enter an IP manually, I’m good to go.

All the branches use separate SSIDs for the 2.4 and 5 GHz bands. Same password for all of them.

The branches use different subnets. So, my saved manual IP only works at the one shop.

I can’t help but think that this is something simple that we’re overlooking.
 
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The branches use different subnets.
That is very, very strange. Subnets are denoted with a subnet mask of the form 255.255.255.0 where the 255s are there to match the first set of numbers in the IP and the 0 is there to allow the DHCP server to assign a number there. Assuming all of the shops use the range of 192.168.1.x, the subnet mask for all of them should be 255.255.255.0.

Now if you are saying that the various shops differ in the way the DHCP is setup, for example, one shop uses 192.168.1.x and another uses 10.0.0.x, then the subnet mask for both of them still would be 255.255.255.0.

So what, exactly, are you doing with this subnet setting?
 
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I think you’re confusing subnet with subnet mask. They all use the same subnet mask (255.255.255.0), but they each use a different range of IP addresses. One uses 192.168.0.1/24, another uses 192.168.1.0/24, etc.
 
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I know the difference. I was involved in networking before the WWW came along, back when DARPA ran the net. Back before HTTP. I posted what I did because you said
Here's the only thing that has worked for me:

Configure IP: Manual
Enter an IP address that I think will work
Enter a Subnet Mask appropriate for the above IP address
Enter the router IP
Configure DNS: Automatic
I added the emphasis there to show what triggered my comment. When I looked at my iPhone, the default subnet mask was 255.255.0.0, but if they are using a Class C subnet (very highly likely and consistent with the IPs you have posted so far), then the mask should be 255.255.255.0. 255.255.0.0 won't connect because the third byte will be zeroed out at the logical ANDing. Given you used CIDR notation, I gather you know that already. And I assume that by this
One uses 192.168.0.1/24, another uses 192.168.1.0/24, etc.
you are saying that they use 192.168.x.y across the shops, with some using 1 for x and others using 0 for x. The defined private range for that private subnet is 192.168.0.0 to 192.168.255.255 or (CIDR 192.168.0.0/16),but usually managed as 192.168.x.0/24. So in one shop the range of addresses would be 192.168.1.2-255 (1 is reserved for the router) and in another it might be 192.168.0.2-255.

Do you know what model of ZTE wireless router it is? From their website, they have a broad range of devices. Given all that you have done, there must be some setting in the router that is not negotiating with your particular phone. I think it's been asked already, but do you have any security software that the ZTE might be in conflict? I don't know a lot about Chinese routers, but have heard stories about some Chinese equipment not liking anything that looks like privacy protection.
 
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Do you know what model of ZTE wireless router it is? From their website, they have a broad range of devices. Given all that you have done, there must be some setting in the router that is not negotiating with your particular phone. I think it's been asked already, but do you have any security software that the ZTE might be in conflict? I don't know a lot about Chinese routers, but have heard stories about some Chinese equipment not liking anything that looks like privacy protection.

The router is up on the ceiling so I can’t see what model it is.

I’m not using any extra security software on either my iPhone or iPad.

My daughter started working at this company about a month ago. During that time she has been assigned to five or six of their shops. She has an iPhone. She has no trouble connecting to the WiFi at any of the shops.

As I recall, all of the shops use Class C subnets.

I think it’s time to drop this now.
 
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I think it’s time to drop this now.


Well, it seems that at least you can usually connect most times according to your post #23.

And I assume trying the Wireless Diagnosis didn't help very much, if at all???

It would be interesting to know what the difference is between your device and your daughters, considering that she is able to connect without any problems. But I guess that's the whole gist of this thread eh???

Or maybe you're just actually blacklisted somehow, but then you would probably be curious to know why???? :Smirk:



- Patrick
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Maybe because others don't go to multiple locations?
 
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chscag

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Please note that member "Ratsima" has requested that we end this thread. Let's close it now.

Thanks to all who participated.
 
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