macOS Sequoia LAN is totally unstable!

Update on my above situation. As suggested by many in this thread, uninstalling Little Snitch restored networking and allowed me to complete Time Machine backups to NAS. Reinstalled Little Snitch as a test: all the issues returned. I haven't tried keeping Little Snitch + disabling MacOS firewall yet... I'll wait for 15.1 before trying that.

From what I gather this is happening at a very low-level of the network stack (probably the transport layer), affecting wired and WiFi networking.

Hi,

I faced the issue with the lan access from the apps that aren't of Apple, for example Chrome, Termius (ssh, sftp client) and so on.

In particular I get problems when I try to access in HTTPS or SSH to a local resources like Raspberry, internet router or switch.

To temporary resolv the issue (when it appear), I have to deactivate and reactivate one app from the lan access from system setting -> privacy and security -> Local Network (I hope those are the right names of the menu, I'm not have the engligh language on my mac).

With Safari or terminal I can access to local resources in HTTPS or SSH without any problem.

I think the problems are due to the Network Access feature that it doesn't works right.

[Edited by Moderator]

Here are some things to try:

1) Make sure System Settings > WiFi > Private WiFi Address is set to "fixed"

2) Make sure you aren't running any kind of firewall or network filter.

3) Make sure you aren't running any kind of 3rd party "security" or "privacy" app

4) Go through #2 and #3 again. Yes. "Little Snitch" belongs in this category too.

and as of today

5) Update to Sequoia 15.0.1. Supposedly it works better with some of those 3rd party security apps.

Edit: totally spaced this out

2a) Make sure you aren't running any kind of VPN. Some of them work. Some of them don't.

Many of us prefer not to allow unrestricted inbound traffic to our machines. Personally, I set my system to block all incoming connections by default and only allow specific ones as needed. Since upgrading to macOS 15, however, I’ve been struggling to keep an SSH session open for more than 30 seconds before encountering “Bad packet length…” errors, followed by “Connection corrupted” and a terminated session.

Uninstalling Little Snitch and disabling the built-in firewall did resolve the issue for me temporarily, but I agree with @idjwert that suggesting users disable all firewalls and security software is generally poor advice. Solutions to connectivity issues shouldn’t involve turning off essential security measures—especially when users may not have a choice, like those on company-provided machines where disabling firewalls may be prohibited. I don’t allow users to disable the firewall on our company laptops for this reason.

I even attempted to revert to Sonoma, willing to sacrifice a few new features rather than risk exposure on the public internet, but this wasn’t feasible as key apps, including Mail and Photos, no longer functioned correctly due to database changes.

In the end, I temporarily disabled my firewall and uninstalled Little Snitch, accepting a calculated risk that’s mitigated by my control over network firewalls at home and work. However, I’m strictly avoiding public networks until this issue is resolved.

Don't know why my few replies are disappeared. I have the exact issue with my Macbook Pro 16(2019). What I have to do is " make inactive" all the network connections (WiFi, wired Ethernet) and "Make active" again.

I had both ethernet and WiFi on (ethernet first in service order). I had a web page that would not load most of the time so I turned off WiFi and now no issues just using the ethernet connection.

etresoft wrote:

Here are some things to try:

1) Make sure System Settings > WiFi > Private WiFi Address is set to "fixed"

2) Make sure you aren't running any kind of firewall or network filter.

3) Make sure you aren't running any kind of 3rd party "security" or "privacy" app

4) Go through #2 and #3 again. Yes. "Little Snitch" belongs in this category too.

and as of today

5) Update to Sequoia 15.0.1. Supposedly it works better with some of those 3rd party security apps.

Edit: totally spaced this out

2a) Make sure you aren't running any kind of VPN. Some of them work. Some of them don't.

Suggest that you do NOT update to Sequoia 15.0.1 it has spread these problems to droves of users who weren't having them before. 15.0.1 will not keep stable network connections with the firewall enabled. It may have something to do with running Little Snitch at the same time - if you have Little Snitch properly configured, you don't need the Apple firewall. Suggesting people run without any firewall at all, or without their security apps, is TERRIBLE advice. ABSOLUTELY TERRIBLE.

QINirvana wrote:

I am still having the same issue. The apps aren't from Apple unable to access the local network like Chrome /Edge access to router/NAS/Shared folder after the reboot until I switch them off/on from local network(Privacy & Security). But the apple apps like Safari etc. have no issue.It is happening every time I reboot the laptop(A2141 Macbook Pro 16 2019)..

This doesn’t seem related. Your case works, and your connections are stable. Here, something is resetting the third-party apps’ network permissions, or maybe there’s a corruption of the permissions data.

For the deep technical details of what you’re encountering, see: TN3179: Understanding local network privacy | Apple Developer Documentation

If there are add-on security apps, add-on firewall apps, add-on on VPNs, add-on cleaner apps, or suchlike, remove all of those per the vendors’ instructions, restart, and test again.

Unfortunately if not some add-on, there’s no means of directly resetting network permissions, and the tccutil (tccutil reset All) doesn’t work for this case. (If you have developer program enrollment, dup fb14944392.)

Has this Mac has ever run a beta? If so, I’d re-install without a restore.

But more generally, this Mac is probably headed for a backup and reset and restore. Hopefully that clears the TCC.

connect to the NFS, SMB, and xRDP services on my Ubuntu 24.04-based home server. They all worked stably with Sonoma until I upgraded to Sequoia, no matter 15.0, 15.0.1 official or 15.1. I think this problem is not protocol-specific but is rooted at something wrong down below the Transport Layer.

It because you using two different clock syncing from your Mac to the NAS! You should use the same clocking on both devices! Clocking to NAS with two different clock sources means trouble over Time! So use a Federal sever instead off two different clock sources clock sources, this a Very old problem through the years even big networks I have been apart 35 years Engineer!

I am still having the same issue. The apps aren't from Apple unable to access the local network like Chrome /Edge access to router/NAS/Shared folder after the reboot until I switch them off/on from local network(Privacy & Security). But the apple apps like Safari etc. have no issue.It is happening every time I reboot the laptop(A2141 Macbook Pro 16 2019)..

There is clearly an SMB issue going on as I've had similar experiences with SMB related disconnects trying to run previously working Time Machine backups to my Synology, 15.01 is clearly at fault. I had SMB issues (disconnects/Finder crashes) on Mac OS 14, but this only occurred when I had Time Machine running a backup while also transferring files to my Synology.

[Edited by Moderator]