Big Sur reproducible DNS resolution issues

Just to add to this thread - also experience the same problem since upgrading to BigSur in the last month. No issues before upgrade. Have to reboot several times a day to resolve. Network connectivity completely drops out through both wired and wireless. Problem does appear to be DNS - browser cannot resolve hostnames. I have noticed that often the problem is triggered when I start Docker Desktop, however I have had it intermittently fail at other times (presumably when some other service starts that I haven't been able to identity?)

Just to add to this thread - also experience the same problem since upgrading to BigSur in the last month. No issues before upgrade. Have to reboot several times a day to resolve. Network connectivity completely drops out through both wired and wireless. Problem does appear to be DNS - browser cannot resolve hostnames. I have noticed that often the problem is triggered when I start Docker Desktop, however I have had it intermittently fail at other times (presumably when some other service starts that I haven't been able to identity?)

I also experienced a DNS-related issue when using ssh to connect to my work remote server, both on BigSur 11.3.1, and even now after an update to 11.4. In my case the issue manifests with an ssh connection hanging for an infinite amount of time on my mac, while it works flawlessly when using other computers (also when connected to the same wifi network as my mac). Strangely, despite the ssh connection doesn't work, pinging or browsing the web pages hosted under the same server do. Eventually I had to use a workaround solution, which was to do ssh using the IP of the target server instead of the domain name.

I noticed I get the issue when I connect (disconnect?) my iPhone to my mac book. DNS became broken for my VPN so I must restart the connection.

I also experienced this weird DNS resolution problem. It appeared to me as more than one second of wait time for a web page. I was able to reproduce the behavior in Safari, Firefox, and Chrome. Both Norton VPN, which is included in Norton 360, and AnyConnect have this weird problem.

See my answer here: https://developer.apple.com/forums/thread/667347?answerId=682255022#682255022

Quick Fix: Change your power plan and disable sleep mode (or greatly extend the timeout for it) on connected to power & to what you can tolerate on battery, understanding this will impact battery life for the latter.

This seems to prevent the bug from triggering.

Note - I have zero issue like this on my M1 Mac that does NOT have Cisco VPN installed. (Both are M1's, one's a pro and one's an air since I didn't need the extra GPU.)

This problem has been bothering me on my corporate MacBook Pro since I got it. As people in this thread, I've been frequently rebooting to temporarily fix the problem. Today, after upgrading to macOS 12, the problem started occurring almost instantly after logging in. E.g. I could search for something in Google, only to find that DNS resolution was already broken when trying to open one of the results.

I then remembered something they taught us 20 years ago, during our training for first line support for the largest Belgian ISP: remove the network adapter in device manager, then reboot and reinstall the driver. This was obviously a solution for Windows problems, but I figured it couldn't hurt to try doing something similar on macOS. So I went to the Network settings, removed the Wi-Fi service, rebooted, and afterwards created a new Wi-Fi service. I have about 4h of uptime since then, and DNS resolution is still working. Too soon to tell if it really fixed the longstanding issue, but going from breaking in just minutes to have working DNS resolution for hours definitely looks promising.

mDNSResponder is just a disaster constantly have to unload/load, why not keep it simple and go back to /etc/resolv.conf

I upgraded my macbook to 2021 Pro M1, no lucks, already tried every solution here, no one works for me.

I am also experiencing this problem, not sure, but likely since I updated to Monterey last week or so. I am on an 2016 MacBook Pro. I also have Cisco VPN installed, I'm curious if this is the case for everyone?

Still, this is really an disastrous issue, having to restart the MacBook about twice every day, often times at occurrences when I am busy and need the MacBook to work.

Same thing has been happening to me. I have Cisco AnyConnect installed, as well as Little Snitch. After upgrading to macOS 12.2 problem is more frequent. The only thing that works for me is a reboot.

I am having the same issues. I've been using Cisco AnyConnect since macOS 12.1, now on 12.2, and the only thing that is reliable enough, is a restart.

Not VPN Client rated so related, I have the same issue using GlobalProtect, only reboot usually helps super annoying…

In our corporate network moving to Big Sur took much troubleshooting and developing a matrix to resolve. With Cisco AnyConnect installed with Sophos Endpoint protection essentially broke DNS on the machine, our domain was no longer reachable. The system extensions on the same machine clashed causing the issue, after much troubleshooting removing either of the system extensions resolved the DNS issue.

https://www.cisco.com/c/en/us/td/docs/security/vpn_client/anyconnect/anyconnect49/upgrade/AnyConnect_macOS_BigSur_Advisory.html

https://community.sophos.com/intercept-x-endpoint/f/recommended-reads/116397/sophos-mac-endpoint-how-to-configure-jamf-privacy-preferences-for-10-15-compatibility

I logged support requests with all vendors, we decided to move away from Sophos Endpoint and use Jamf Protect with no system extensions / DNS issues.