Temporary loss of network connections during backup

My setup:

  • 13" MacBook Pro 2020, macOS Ventura 13.5
  • iPad 8th gen, iPadOS 16.6 - used as an external display via WiFi
  • WD PR2100 NAS with TimeMachine enabled


Steps to reproduce:

  1. Start browsing the Internet*
  2. Start a TimeMachine backup
  3. Keep browsing during the backup process

*) This is just an example, all apps relying on the Internet connectivity are affected.


Actual behaviour:

  • at some point, usually close to end of the backup process, the following happens:
    • secondary display (iPad) disconnects
    • browsing the Internet not possible due to network loss
    • not able to reach devices within the network, i.e. access the router via its IP address
  • wait about 2-5 minutes and everything is back to normal - iPad reconnects (either automatically or needs to be done manually), network comes back up

NOTE: all other devices connected to the home network (WiFi and Ethernet) are fine and their connectivity remains uninterrupted


Expected behavior:

  • no service or functionality get interrupted by the TimeMachine backup process


Attempts to resolve the problem (and neither of these improved anything):

  • switched over to a cable connection to see if this is only happening when on WiFi
  • enabled throttling on the port the NAS is connected to the router
  • restarted all the devices
  • configure TimeMachine from scratch


I've had this issue for over a year now, so across number of macOS versions as well. And generally all the devices involved (iPad, MacBook, router, NAS, AP) are constantly kept up-to-date with latest software/firmware.


It would be great to work out how can we narrow down what the root cause might be avoiding reinstalling the OS, as due to certain factors I'm not able to do that.

MacBook Pro 13″, macOS 13.5

Posted on Aug 7, 2023 8:48 AM

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33 replies

Aug 7, 2023 8:57 AM in response to cwieku

In my opinion, the last steps of your backup ACROSS YOUR NETWORK to your NAS are overwhelming your network connection, especially if your only network connection is over Wi-Fi.


If you hold down the Option key, you get a snapshot of your Wi-Fi operating conditions, like this older one. Transcribe or screenshot your results for assistance:



Aug 7, 2023 9:59 AM in response to Grant Bennet-Alder

Thanks for sharing your thoughts!


Unfortunately this was one of the cases I had taken into consideration. That was the reason why I decided to switch to a cable connection and at some point also enabled bandwidth throttling on the respective ports. And it didn't help at all.


I should have probably also mentioned that the WiFi layer is separated from the router - I have a UniFi U6 AP connected to a MikroTik hAP ac^2 router. I consider this setup as pretty decent for home office usage. Also the WiFi isn't overwhelmed in terms of number of devices and traffic, as when the issue occurs there's usually only the iPad and my iPhone connected to it.

Aug 7, 2023 11:22 AM in response to cwieku

While there have been a few reports of ENTIRE home networks being overcome with traffic from one computer, I think such instances are likely rare.


from your description, it still sounds like that same computer's connection to things around it on your home network are being swamped by that data during the late stages of backup.


Tell me about all the internet connections to your Mac, and in particular, which connection is TOPMOST in


System Preferences > network



.

Aug 7, 2023 11:46 AM in response to Grant Bennet-Alder

The topmost connection type is Ethernet over Thunderbolt. And a note on this one, I've been using 3 different expansion hubs with Ethernet and none of them made any difference. Currently I'm using CalDigit TS3 Plus.


The second from the top is my WiFi. Currently active, but disabling it and using only the wired connection didn't make any difference.


It really feels like due to the amount of data or something else that's happening during those later stages of backup, causes some kind of restart to certain services, drivers or whatnot. The interesting bit though is this happens DURING the backup process, not after, and it still succeeds, while nothing else can access the network.

Aug 7, 2023 12:14 PM in response to Grant Bennet-Alder

The dock has multiple different connection types on it. The ones I'm using are only the Ethernet and DisplayPort.


Nevertheless I wouldn't be focusing on the dock itself as something what contributes to the problem simply because I've only been using it for 2 weeks. My thinking keeps leaning towards the OS itself, but I'm struggling to find a way to diagnose the problem from this perspective. Reinstalling OS would be the quickest option, but again, I can't do that.

Aug 7, 2023 1:14 PM in response to cwieku

A display running over DisplayPort 1.2 as supported by that display, at 3440 by 1440 at 100 Hz using 8-bit color consumes HBR2 data rate of 17.28 G bits/sec.


A thunderbolt connection has 40 G bits/sec total available, so you are dedicating about half the total ThunderBolt bandwidth to the display.


---------

what speed is your Ethernet connection running at?



Aug 8, 2023 6:47 AM in response to cwieku

when you run into problems like this, you should completely remove (not just disable) any User-installed VPN software.


User-added VPN software is known to meddle in MANY things, far beyond its stated scope. In addition, it may be sending your local traffic out to the Internet and back, and that can't possibly be as fast a local traffic.

Temporary loss of network connections during backup

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