macOS 26.6+ updates over cellular hotspot blocked by software update policy

The softwareupdated log entry showing allowsCellular:NO indicates that macOS did not allow the normal Software Update scan to use the cellular connection. 

Since the same update appears immediately when you switch to ordinary Wi-Fi, the difference is clearly related to the type of network connection.

Before testing anything else, make sure Low Data Mode is turned off for your iPhone hotspot and, if you use it, the iPhone USB connection. 

Apple explains the relevant Mac network settings here: Change network settings on Mac and Low Data Mode on iPhone here: Use Low Data Mode on your iPhone and iPad.

While connected to your cellular connection, run: the Terminal command  softwareupdate --list-full-installers

This will show the full macOS installers currently available for your Mac. 

If it lists a newer Tahoe 26.x release, for example, 26.6.2, you can test downloading it with: softwareupdate --fetch-full-installer --full-installer-version 26.6.2

Though the current version of Tahoe is 26.7.1 you would house this Terminal command : softwareupdate --fetch-full-installer --full-installer-version 26.7.1 

Replace 26.6.2 with the 26.x version actually shown by your Mac. Apple documents both commands here: How to download and install macOS.

Keep in mind that , fetch-full-installer only downloads the installer; it does not install macOS or change the Software Update policy. 

If the download succeeds, the installer should appear in /Applications, and you can run it when you're ready to update. 

Because it is a large download, keep the Mac connected to power.

If --list-full-installers does not show a newer Tahoe 26.x release, use only the versions it reports as available for your Mac.

If the download fails over cellular, save the complete Terminal output. 

Combined with the allowsCellular:NO message, that will help establish whether the same restriction also applies to full-installer downloads.

This gives you a supported way to obtain a Tahoe update over cellular, but it does not provide a way to re-enable cellular downloads in the normal Software Update mechanism. 

The evidence currently shows that the policy is being applied, but does not identify a supported user setting for changing it. 

I would therefore avoid modifying softwareupdated, disabling SIP, or changing undocumented system settings unless reliable documentation specifically identifies a supported method for your version of macOS.

My Mac is collected to a cellular network via USB connection to my iPhone

On my Mac I went into Network > iPhone USB > Details and turned off Low data mode and was then able to download software updates

Low data mode was off on my iPhone so this was surprising.

The behaviour you describe is not explained by Apple's current documentation as an intentional restriction on M1 Macs.

Your 16-inch MacBook Pro with an M1 Pro processor is supported by macOS Tahoe. 

Apple continues to list Apple-silicon MacBook Pro models from 2020 onward as compatible with Tahoe, and Apple is still releasing Tahoe updates, including macOS Tahoe 26.7.1, released September 28, 2026. (Apple Support)

There is, however, a particularly relevant precedent for your observation. Apple explicitly states that iOS 26.6.2 fixed an issue where software updates performed over cellular would not proceed. 

Apple says affected devices had to be updated using Wi-Fi or a computer in order to receive that fix. (Apple Support)

Your Mac exhibits a very similar pattern: since macOS 26.6, Software Update does not find the available update when the Mac is connected through your iPhone's cellular connection, whether by Personal Hotspot Wi-Fi or USB tethering. When you connect the same Mac to conventional Wi-Fi, the update is found normally.

That establishes a clear and reproducible connection-dependent Software Update problem, and the timing is particularly noteworthy because iOS 26.6 had a documented cellular Software Update problem. 

However, Apple has not published documentation identifying an equivalent macOS problem, nor has Apple stated that it deliberately prevents M1 Macs from receiving updates over cellular connections.

It is therefore reasonable to report the issue as: “Since macOS 26.6, Software Update does not detect available macOS updates when the Mac is connected to the Internet through an iPhone's cellular connection, either by Personal Hotspot or USB tethering, although the update is detected immediately over conventional Wi-Fi.”

Apple's relevant documentation is macOS Tahoe compatibility, macOS Tahoe updates, Apple security releases, and iOS 26 enterprise updates. 

Glooed wrote:

Since macOS Tahoe 26.6, I cannot update the Macbook Pro 16" (M1 Pro, 16 GB RAM, 1 TB SSD) via cellular data, neither over iPhone's Wi-Fi hotspot, nor USB tethering. When I visit System Settings > Software Update and click Check for Updates, looking for update takes a long time (10 minutes approx.) then reports "Your software is up to date".

If I connect to a standard non-cellular Wi-Fi, the update comes instantly.

I have checked and found out with terminal command

log stream --info --predicate 'process == "softwareupdated"'

and issued

softwareupdate -l --verbose

when connected over cellular 5G Wi-Fi, and also USB tethering to find out there's Software Update policy that restricts my Macbook from downloading updates over cellular.

SUCorePolicySoftwareUpdateScan(

...

allowsCellular:NO

...

)

How to fix that and help myself to download software updates again? I'm often on the way and have trouble getting to reliable Wi-Fi that allows huge downloads like macOS software updates, while my 5G plan is unrestricted and fast. Up to version 26.6, everything worked as expected and I have updated over cellular connection (Wi-Fi/USB tethering) without any problems.

My device is supported and I have enough disk space, it wouldn't work over Wi-Fi without.

My cellular provider isn't blocking apple software update servers in any way, that is confirmed with them personally and by testing.

I won't update to macOS 27 until the major update release is out, will stay on Tahoe for now.

hmmm.... interesting you have distilled this down

I can say I have had similar update issue checking "on cellular" starting with 26.6.1, 26.6.2, 27.0 on Intel MBP

To be proactive you can file a bug report / submit your Apple Feedback here: Product Feedback - Apple

You can Call Customer Support (800) MY–APPLE (800–692–7753)

or on line https://getsupport.apple.com/

Outside the USA—Contact Apple for support and service by phone

See a list of Apple phone numbers around the world.

Contact Apple Support - Apple Support

The current macOS Tahoe is 26.7.1

the current Golden Gate is 27.0.1

Glooed wrote:

I now have a strong feeling this actually might be a deliberate undocumented decision made by os developer, since M1 lineup will most likely stop being supported soon.

From what I can see the first M1 model to be discontinued was done in 2022 according to MacTracker.... which means all M1 models are fully supported at least until some time in 2027 as Apple supports the hardware for 5 years after a product has been discontinued, plus another two years of partial hardware support. Some M1 models were only discontinued in 2024 which means full hardware support for those particular models until at least 2029 (partial support until 2031).

Of course macOS typically stops once full hardware support is gone, but there is no hard & fast rule here for macOS support. If Apple releases macOS for a product, then that macOS version is fully supported. Perhaps some new fancy feature may not be supported on the older hardware, but that tends to be very limited.