How can I downgrade from macOS Tahoe 26 to earlier version on MacBook Pro?

I am having issues after installing macOS Tahoe where my vpn disconnects about every 10 minutes. I searched online and this is a known issue where Mobile VPN with IKEv2 connections that worked previously might disconnect after 10 minutes.

Anyone have any recommendations on how to fix this?

Commercial VPNs ?

They may not be what one believes they are doing for the computer / mobile device

What they actually are doing behind the scenes  and unbeknownst to the user

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

good to know. I had no idea that was an issue. thanks for informing us (me) of that. :)

thanks. that's why I asked. I often am not thinking about things I don't use, such as "locally-stored email attachments, etc".

whitemagnolia wrote:

I am having issues after installing macOS Tahoe where my vpn disconnects about every 10 minutes. I searched online and this is a known issue where Mobile VPN with IKEv2 connections that worked previously might disconnect after 10 minutes.

Anyone have any recommendations on how to fix this?

This is a not infrequent issue that surfaces ... namely a VPN that worked with older MacOS stops working with the newer MacOS. There are three choices:

(1) update the VPN to a newer version that works with Tahoe (this may or may not be possible)

(2) switch to a VPN that works with Tahoe

(3) best -- stop using a VPN, see Owl-53's post prior to mine on this. If your employer requires a VPN, then go back to options 1 or 2, but most employers provide a custom configured VPN that is tested and reliable on the MacOS it is intended to be used with ... and those setups do not steal user's personal data, as opposed to many commercial open market VPNs that do exactly that.

In my opinion (not all share this opinion), if you are using a VPN to avoid locations-specific limitations of licenses and use, then that is skating on thin ice and something to avoid.

If your employer or financial institution or university require a VPN, contact them for a recommendation. Tahoe has been out for a while and should be well known for compatibility purposes.

t3w wrote:

1. re why want to downgrade aka revert OS.

got it via a bug; wasn't ready for this major upgrade and didn't click on it; 100% clicked on a Sequoia upgrade.

I believe that neuroanotomist has elegantly shown what no doubt happened, with their clear explanation and screenshots. I have MANY times updated to a higher version instead of UPGRADING to a new MacOS (I have done that with Sequoia 15.7.2 recently instead of going to Tahoe.) Maybe lesson learned, maybe Apple should be clearer ... but it's done now. I am convinced it is not a bug but an unfortunate example of operator error where someone was confused by the user interface.

2. Now canNOT rename files while viewing in Preview. It lets you change name but doesn't save the new name. When you take a bunch of similar screenshots, it is too difficult to distinguish which is which from the file's icon.

This seems like a minor item that will almost certainly be fixed in a future update. I would classify it as "annoying but can live with it for now."

3. in System settings for Storage, it still hadn't calculated how much space its own System was using after 3 hours.

That has happened to scores of users under older versions of MacOS for years. I have Macs that also have this issue and others that do not. That way of calculating Storage is inaccurate anyway, there are much better ways, certainly not a reason to wipe a disk and go backwards to an older macOS.

Thus want to revert aka downgrade OS, which seems to require wiping machine and starting from scratch = not feasible.

It's the only way. SO if that is "not feasible," you stay with Tahoe. You must wipe machine to go back to Sequoia. But you then need to copy your files off first so you can copy them back after the downgrade.

HOWEVER -- it might be more complicated than "just" wiping the machine. See rbtpt's post which may have been largely unnoticed here, I am quoting from rbtpt:

"Even when you do this process, you will have Sequoia running on Tahoe firmware (preboot/recoveryOS/1TR). To really get back to Sequoia, you would need access to another M series Mac running Apple Configurator 2 and a data/charge USB C cable. Apple Configurator 2 would download an .ipsw Sequoia file. Details here."

So that adds yet another wrinkle.

Bottom line -- I believe (my opinion) you are much better off staying with Tahoe and living with two very minor behaviors which have little impact. Versus wiping your Mac, running Apple Configurator 2, and so forth.