Mac Mini M1 internet speed dropped after Tahoe update

ottiedotbe wrote:

I only have nordvpn installed and I use it quite frequently. Even when it's disabled, speed doesn't change.

No third party firewalls or network protection tool.

Just CleanMyMac.

Part 1 of 3

Commercial VPNs 

They may not be what one believes they are doing for the computer and what they actually are doing behind the scenes and unbeknownst to the user ( you ) 

They may also reduce your Internet Speeds by upwards of 30% 

https://gist.github.com/joepie91/5a9909939e6ce7d09e29

VPN: What you need to know - Apple Community

Part 2 of 3

Any of the below should be removed as per Developers Instructions 

Disk Cleaner 

CleanMyMac , aka “ BrickMyMac “

Part 3 of 3

There are two schools of thought when dealing with CleanMyMac aka “ BrickMyMac “

The steps in #1 below is predicated on the Offending  Application has been Removed as per the Developers Specific Instruction 

# 1 Some Contributors suggest restarting in Recovery Mode and choosing to Reinstall the Operating System over the existing installation. 

This may or may not replace elements of the  Home Folder ( User Account )  and replace any corrupted or removed elements and make things right.

#2 - Then there are Other Contributors ( like myself ) would suggest  from this link Use Disk Utility to erase a Mac with Apple silicon.

Thereafter to start from scratch and install all Required Applications directly from the Apple Apps Store or Directly from the Developer.

If going this route - I suggest Not using Startup Assist to migrate things back as this will probably Re-Introduce the existing  issue at the time TM Backup was made 

No issues here using a M2 Mac Mini with Tahoe 26.2 nor on a M4 Mac Mini Tahoe 26.2 and lastly M4 15" MBA Tahoe 26.2

Uninstall

1 - VPNs (WireGuard, Nord, Tailscale, etc.)

2 - Third Party 2 Way Firewalls like Little Snitch / Lulu

3 - Antivirus / “network protection” tools which Totally useless software

ottiedotbe wrote:

Just did the whole networking process analysis with chatgpt afeter removing nordvpn and in safe mode.

This was the result :

✅ FINAL CONCLUSION

🔴 macOS Tahoe 26.2 (build 25C56) has a network regression on M1

Specifically in:

• TCP congestion control

• Packet pacing / responsiveness

• Apple Silicon network driver

This is not a configuration issue and cannot be fixed with settings.

Your Mac can physically go faster, but the OS stack keeps it at ~100 Mbps and explodes in latency under load.

That's nonsense from ChatGPT. Rely on it at your own risk. I have 26.2 on both Intel and M1 Mac computers and both routinely get 500 Mbps from our internet provider, who advertises 400 Mbps, so we get a bit faster.

"The OS stack keeps it at 100 Mbps" is nonsense, if it does that, how do we get 500 Mbps where I am.

I find especially amusing the statement by ChatGPT that the OS "explodes in latency under load." I get 500 Mbps in all parts of our residence under severe load or under light load, on all devices, Macs (M1, Intel, M3, M4 ...) with a mesh router. Running 26.2.

I second Owl-53's excellent responses.

If you were using CleanMyMac, my guess (I have no way to really tell what harm has been brought to your Mac by CleanMyMac) is that it "cleaned" out some files sometime in the past and this perhaps was accommodated under older MacOS but those files were needed and their absence is incompatible with 26.2 and thus degraded your Mac's settings for internet.

UUSUALLY, when someone reports "after installing 26.2 my xxx doesn't work well anymore" that ends up being (MOST of the time) due to something set or installed on the Mac that is not compatible with the newer MacOS.

26.2 is not perfect and like all software, still has bugs. But if all Macs were capped at 100 Mbps and exploded in latency under 26.2, most Macs would already be returned to the Apple Store.

steve626 wrote:

ottiedotbe wrote:

Just did the whole networking process analysis with chatgpt afeter removing nordvpn and in safe mode.

This was the result :

✅ FINAL CONCLUSION

🔴 macOS Tahoe 26.2 (build 25C56) has a network regression on M1

Specifically in:

• TCP congestion control

• Packet pacing / responsiveness

• Apple Silicon network driver

This is not a configuration issue and cannot be fixed with settings.

Your Mac can physically go faster, but the OS stack keeps it at ~100 Mbps and explodes in latency under load.

That's nonsense from ChatGPT. Rely on it at your own risk. I have 26.2 on both Intel and M1 Mac computers and both routinely get 500 Mbps from our internet provider, who advertises 400 Mbps, so we get a bit faster.

"The OS stack keeps it at 100 Mbps" is nonsense, if it does that, how do we get 500 Mbps where I am.

I find especially amusing the statement by ChatGPT that the OS "explodes in latency under load." I get 500 Mbps in all parts of our residence under severe load or under light load, on all devices, Macs (M1, Intel, M3, M4 ...) with a mesh router. Running 26.2.

I second Owl-53's excellent responses.

👍

🦉-53

We need to understand some of the Limitations of Ai / LMM

Garbage In will product Garbage Out

AI / LMM is only a super version of Predictive Text that based upon a series of Data Points

Dependent on the number of Data Points, AI / LMM has been known to suggest Resetting the SMC on Apple Solon Computers WRONG - Answer

There has been sufficient advice offered for the User ( you ) to make an informed and educated choice what remedial actions are  required for this computer.

The suggestions have been put forth on a volunteer basis, in good faith and in the best interests of the computer which do not always align with the users’ expectations 

Good Luck

FYI

Using a M4 Desktop, M2 Desktop and M4 Laptop each will Tahoe 26.2

Using 6E Wifi to a Fibre Optic connected Router with 1.5 GB speed

Regularly check the Speed from within the Router to ISP and achieve the Full Service I subscribe to

Also do a www.speedtest.net speed test at least once a day and still achieve Full Speed download and Upload

Have no Commercial VPNs, Disk Cleaners, Two Way Firewalls and for sure No Antivirus Software installed on any of the machines

Go Figure

A typical Side Stepping of the Self Infected issues

The XY problem