VLAN issues after 11.4 update

[KE7ADU]

I have 2017 MBP I have several Thunderbolt 3 docks and use a number of VLANs at work. After upgrading to 11.4 VLANs stopped working in the dock I use at work and the portable Startech dock. The ethernet port and all other functions of the TB3 dock work as normal but when I look a my VLANs they show no adapter in drop down list. I have a cheap Intel bases TB3 dock at home and VLANs continue to work normally.
My install was an upgrade so after the normal NvRAM and PRAM resets with no change I did a clean install of 11.4, no change. I don't have install media for Big Sur prior to 11.4 but once I have back up I my dump Catalaina on here to see if that brings my VLANs back on the other TB3 devices.

Any once with the same issue or fixes?

 

[MrQuery]

Same issue here with a "Belkin Thunderbolt 3 Express Dock HD".
The OS simply no longer reports that this Network Interface supports VLAN's.
It looks like Apple made a driver-update which is faulty and caused the VLAN support to get dropped.
Because I can't get it to work no matter what I do. I even tried fixing the issue by deleting all network-configurations in the /Library/Preferences/SystemConfiguration folder and reconfiguring the system, but that sadly didn't help.

I hope Apple didn't decide to drop support for these network interfaces.
I would also be weird if they did, as this docking station was bought from the Apple Store itself and wasn't cheap.

Did anyone find a solution yet?

UPDATE:
I can tell from the "pre-update" version of the file "/Library/Preferences/SystemConfiguration/networksInterfaces" that since the update the system is using a new network-driver.
I tried re-using the old driver, but that doesn't seem to work (it reverts back to the new driver.)

I contacted Belkin and they were not aware of the issue, but were very helpful and a ticket was created in an attempt to find the cause and hopefully a solution. Let's hope Belkin support will save the day ;-)

 

[JC Denton]

I've got this same issue on a CalDigit TS3 Plus dock. I filed a bug report with Apple.

 

[KE7ADU]

I was so happy with 11.3 because I was finally able to use use VLAN interfaces with Fusion and Parallels, something that broke when I upgraded to Big Sur. If it's not resolved in 11.5 I am seriously considering falling back to Catalina. Broken VLANs is a deal breaker for me.

 

[anshuvorty]

What is the point of VLANs, again? Why do we need that?

 

[KE7ADU]

What is the point of VLANs, again? Why do we need that?

If that's a serious question you probably don't need them or have someone else to set them up for you. If you actually want an answer I'm happy to provide some scenarios.

 

[MrQuery]

I got an answer from Belkin pretty fast (nice guys and good support).
Sadly they could not help me as the driver used is created by Apple, so it is out of their hands.
They did however file a bug-report at Apple themselves too, as it appears not only VLAN's are affected.

According to them, the problem is with all Thunderbolt based devices and is caused by the need to update all drivers to support their own M1 and the new M2 chips. These updates have broken many other parts and the most common issue heard is a screen flicker on displays connected to thunderbolt display. (Which indeed I experience too.)

I waited to see what the new update to Big Sur 11.15.2 would do, but sadly that offered no solution either.
I'm afraid we need to wait very long before Apple fixes this, it pretty simple for them;
"Fixing bugs for already sold devices won't make them more money, building support for new hardware will."
I don't think Apple will agree with my quote, but as I'm a developer myself, I just know that this is the reality when it come to prioritising what needs to be done first. (I have to do that too.)

I'm also seriously considering installing a fresh install of Catalina which worked perfectly.
Sadly that means letting go of some other improvement in Big Sur that I would mis.
Especially the better and improved TouchBar features are quite useful for me.
So, I'm still doubting (also because I hate to think about the extra work it would cost me. )

 

[KE7ADU]

I got an answer from Belkin pretty fast (nice guys and good support).
Sadly they could not help me as the driver used is created by Apple, so it is out of their hands.
They did however file a bug-report at Apple themselves too, as it appears not only VLAN's are affected.

According to them, the problem is with all Thunderbolt based devices and is caused by the need to update all drivers to support their own M1 and the new M2 chips. These updates have broken many other parts and the most common issue heard is a screen flicker on displays connected to thunderbolt display. (Which indeed I experience too.)

I waited to see what the new update to Big Sur 11.15.2 would do, but sadly that offered no solution either.
I'm afraid we need to wait very long before Apple fixes this, it pretty simple for them;
"Fixing bugs for already sold devices won't make them more money, building support for new hardware will."
I don't think Apple will agree with my quote, but as I'm a developer myself, I just know that this is the reality when it come to prioritising what needs to be done first. (I have to do that too.)

I'm also seriously considering installing a fresh install of Catalina which worked perfectly.
Sadly that means letting go of some other improvement in Big Sur that I would mis.
Especially the better and improved TouchBar features are quite useful for me.
So, I'm still doubting (also because I hate to think about the extra work it would cost me. )

I rolled back to Catalina after migrating my BigSur install to an external SSD. I do miss a few of the of the features in Big Sur but not enough to make me give up VLANs. So, now when an update for Big Sur is released I boot to my SSD and see what happens. So far they are still broken. Maybe it will be better with Monterey but I’m not holding my breath.