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User profile for user: dxlc0
dxlc0 Author
User level: Level 1
4 points

iPhone Personal Hotspot partially works, DNS, DHCP and port-blocking?

Hi, everyone!


I've got an iPhone SE 2nd Gen on Ting Mobile. It has Personal Hotspot capability, and I called Ting to confirm that they do not block any traffic.


The iPhone SE can connect to the internet and do everything (web browsing, IMAP/SMTP emails). It also seems to allow devices to connect to the Personal Hotspot over Wifi.


I have a 2016 Macbook Pro that I try to tether to the iPhone SE. It used to work perfectly, but a few years ago, some update either to iOS or macOS broke the Personal Hotspot.


Now, the MBP can't access the internet at all on the iPhone SE's hotspot. I have tried all the tips already from resetting the network settings on the iPhone to deleting the iPhone's SSID from macOS to using a direct USB connection. The MBP always gets an IP address of 192.0.0.1, the iPhone always acts as if the MBP is connected to the hotspot, but the MBP can't access the internet. I have tried running nslookup in Terminal on the MBP and that fails.


Then, I got a second device, a LINUX tablet, and connected that to the iPhone SE's hotspot over WiFi. It does a bit better. It can browse any website using the web browser. It can run nslookup and resolve names. ssh kind of works, but only if I use the IP address of the server, not a FQDN. But IMAP/SMTP in Thunderbird do not work.


So, I have learned that at least the iPhone with Ting can pass DNS, HTTP/HTTPS, and ssh traffic just fine. But there appear to be serious problems that prevent the normal use of the hotspot.


It looks like two or three problems together, probably something wrong with DHCP, DNS, and perhaps port-blocking.


Any input is welcome. I don't see many discussions of this issue, though there are a few "iPhone Personal Hotspot doesn't work" threads with lots of "Me Too" votes. None of them dig deeply into command line diagnostics that could help solve the problem.


For now, I need to get a hold of a second iPhone or a second mobile carrier's SIM card with known-good mobile data plan (known to not block any traffic). It would be nice to get a second Macbook too, but to some degree, the LINUX laptop can serve that purpose. If I get everything working on the LINUX laptop with the iPhone, that would implicate the Macbook Pro.


Thanks in advance for any help you may provide!

iPhone SE, iOS 17

Posted on Jul 9, 2024 6:14 PM

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User profile for user: Mac Jim ID
Mac Jim ID
User level: Level 8
38,081 points

Jul 9, 2024 6:37 PM in response to dxlc0

Just to verify your settings. After you are connected to the HotSpot, click Wifi in Settings and choose Details next to the Hotspot network. You should have an IP Address along with a Router Address on that page. Choose TCP/IP in the sidebar and verify:

Configure IPv4 - Using DHCP

Configure IPv6 - Automatically


Your Mac is not getting the correct IP Address.


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User profile for user: dxlc0
dxlc0 Author
User level: Level 1
4 points

Jul 9, 2024 8:08 PM in response to dxlc0

UPDATE 1: Macbook Pro has macOS Monterey 12.7.5.


iPhone has iOS 17.5.1


LINUX laptop got IP 172.20.10.5/28 when working.

I confirm that IMAP and SMTP both work if the IP address of the server is used instead of the FQDN (meaning DNS lookups don't work for ssh nor IMAP nor SMTP, but they do work for HTTP and HTTPS).


When running nslookup, the server used is 127.0.0.53, and it does resolve any FQDN I ask it, obviously going through the iPhone hotspot somehow.



UPDATE 2: I figured out the issue with the Macbook Pro. I had Cisco AnyConnect installed for work purposes, and when I uninstalled it using the included official uninstaller app provided by Cisco, the MBP is now able to use HTTP and HTTPS over the iPhone Hotspot. I suspect the Cisco AnyConnect Packet Filter(s) were messing things up. Emails via IMAP and SMTP also work. nslookup in Terminal works. ssh works too, using the FQDN of the server (DNS lookup works).

So, now the MBP is fully working (as far as I am concerned) with the iPhone Personal Hotspot. The MBP does get the weird 192.0.0.1 IP address, but I guess that is normal since everything works.


Note that I have had Cisco AnyConnect installed on this MBP for years now, and it did used to work with the iPhone hotspot back in the day, though at that time, all three of iOS, macOS, and Cisco AnyConnect would have been at older versions. I guess the way macOS+iOS pull off the Personal Hotspot now is not plain ol' TCP/IP routing but some fancy kind of proxying.


I do need to figure out how to get the LINUX laptop working fully with the iPhone Hotspot, so I will keep updating this thread.


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User profile for user: dxlc0
dxlc0 Author
User level: Level 1
4 points

Jul 13, 2024 12:34 AM in response to dxlc0

This issue may be solved.


I did these additional tests:


1) I hooked up the iPhone via USB to a Gl-Inet travel router, and it worked perfectly. It gave the travel router IP address 172.20.10.3, and the iPhone appeared to serve as the gateway at 172.20.10.1. I tested HTTP, HTTPS, SSH, IMAP, and SMTP, and all worked immediately with proper DNS lookups.


2) I hooked up a Windows PC to the iPhone hotspot via WiFi. It worked immediately on HTTP and HTTPS, but it took longer to get SSH working with proper DNS lookup. This made me wonder: maybe it's not broken but just slow.


3) I went back to the LINUX laptop and connected it to the iPhone hotspot via WiFi. As before, HTTP and HTTPS worked immediately, with proper DNS lookups. Then I tried SSH and IMAP/SMTP with DNS lookups, and as before, it looked like it was not working. I kept waiting, and after a very long time, both SSH and IMAP started working with DNS lookups.


So it looks like non-Mac clients connected to the iPhone hotspot via WiFi just take longer for SSH and IMAP/SMTP. That said, the travel router worked right away, and it has a LINUX OS, but it is connected via USB.


As it is, the slowness isn't great, but as long as it connects, I am able to work. This problem seems to have been solved.

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iPhone Personal Hotspot partially works, DNS, DHCP and port-blocking?

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