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DNS failure on Ethernet port only after Sonoma upgrade

After upgrading my M1 Mac mini to sonoma, I encountered a strange fault. On my Ethernet port only, DNS fails. I can ping my router, I can ping an internet ip address, anything requiring name services fails.

DNS works ok if I disconnect Ethernet and use Wifi, or if I use a USB Ethernet adapter. Just fails on the internal Ethernet adapter only.

I have tried deleting and re adding the Ethernet connection in settings, apple support just suggested is reinstall, but would like to know if anyone else has had this failure.

Posted on Oct 7, 2023 10:05 PM

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Posted on Oct 8, 2023 11:45 AM

Every other device on the network is looking up DNS correctly. The problem immediately occurred after upgrading the Mini to Sonoma. No other changes were made to the network, and devices on my network have been fairly happy like this for 10 years or so. Im guessing it is MUCH more likely there is a bug in the Sonoma upgrade process, and might be a fairly rare condition, As only Minis, and iMacs have ethernet ports now, most people probably just use Wifi.

Eitherway, starting and stopping the firewall on MacOS seemed to clear the fault, and as only DNS services were impacted (to ANY DNS server, not just my local router and DNS servers) it seems much more likely that UDP port 53 was being blocked somehow on the ethernet port. I was able to browse a local web page via an IP address (config page on the router), so I know traffic was passing normally otherwise.


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Oct 8, 2023 11:45 AM in response to MrHoffman

Every other device on the network is looking up DNS correctly. The problem immediately occurred after upgrading the Mini to Sonoma. No other changes were made to the network, and devices on my network have been fairly happy like this for 10 years or so. Im guessing it is MUCH more likely there is a bug in the Sonoma upgrade process, and might be a fairly rare condition, As only Minis, and iMacs have ethernet ports now, most people probably just use Wifi.

Eitherway, starting and stopping the firewall on MacOS seemed to clear the fault, and as only DNS services were impacted (to ANY DNS server, not just my local router and DNS servers) it seems much more likely that UDP port 53 was being blocked somehow on the ethernet port. I was able to browse a local web page via an IP address (config page on the router), so I know traffic was passing normally otherwise.


Oct 7, 2023 10:24 PM in response to Mista2

Mista2 Said:

"DNS failure on Ethernet port only after Sonoma upgrade: I have tried deleting and re adding the Ethernet connection in settings, apple support just suggested is reinstall, but would like to know if anyone else has had this failure."

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Troubleshooting Ethernet:


I. Restart your Router:

  1. Power: off the router
  2. Wait: 30 seconds
  3. Power: It back on


II. Try a New Admin User:

What happens when you create a new administrator user, and log into it? Do you still get this error? If not, then it is likely an error with the current user. If so, then it is likely an error with your Mac.


III. Clear Temporary Internet Files:

Boot into Safe Mode and then Clear your Temporary Internet Files of Safari. Do the same for all ofter Web Browsers you have installed.

Oct 7, 2023 11:20 PM in response to TheLittles

Tried router restart, but didn't expect it to be the problem as every other connected device looking up DNS correctly. Also using a USB ethernet adapter with the same cable and port and the USB Ethernet worked OK.

Already tried a new admin user, no change. It's not a browser problem, NOTHING is able to resolve a name to an IP address on the ethernet port. Not nslookup, or scutil, no local app is able to resolve names when ethernet is connected. I hav restarted the Mini, I have tried safe mode. No change.

However one link I did look at on another site suggested turning the firewall off. This would make sense to me if DNS traffic on port 53 was somehow being blocked by the local firewall with the ethernet as a source. Except that Mac OS firewall is an inbound firewall only, according to the system preferences panel. Anyway, it was already turned off, but there was an options button greyed out, so I enabled the firewall so I could see the options. All the options again, were only to do with Incoming connections, so I disabled the firewall again.

Then tested the DNS on the ethernet again.... and it's now working.

So for me, turning the MacOS firewall on and then off again seems to have corrected the problem.

I just wish I had Wireshark installed at the time as I would have been able to see if DNS traffic was even attempting to go out the ethernet.

Nov 29, 2023 12:10 PM in response to MrHoffman

I had this same issue happen to me on the upgrade. Hoped it would be resolved in the latest release, but it hasn't as far as I can tell. I'm using a USB-C ethernet adapter as a workaround for the moment since I had one handy. I'm seeing the same thing as you. DNS fails. I can access resources directly by IP just fine (ping, ssh, http, https, etc) so routing isn't an issue. I can use the same IP address on my USB ethernet adapter and DNS works just fine. Definitely something got scrambled when we upgraded to Sonoma and I wish someone could figure out what so we could fix it.

Oct 7, 2023 11:20 PM in response to Mista2

Mista2 Said:

"DNS failure on Ethernet port only after Sonoma upgrade: [...]So for me, turning the MacOS firewall on and then off again seems to have corrected the problem."

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Troubleshooting Ethernet:

If firewall is the culprit, then something is likely taking up network traffic. So, for whatever reason, this connection is seen as suspicious.


Disable a VPN:

Are you using a VPN? If so, see about disabling it.

Oct 7, 2023 11:59 PM in response to Mista2

This seems like it might be an IP routing or configuration issue.


Are you using your own local DNS server (unlikely, but possible), or (more likely) are you using your ISP router as a DNS resolver?


How many IP routers are in use here? Usually an ISP router, and maybe also a second and separate router for Wi-Fi?


How many network segments, and how many IP subnets are in use?

Oct 8, 2023 12:19 AM in response to MrHoffman

Fibre cable modem, connecting to a router. The router has 5 ethernet posts, and 2 Wifi networks, 5Ghz and 2.4Ghz. Modem connects to external ethernet port on the router, my Mac mini, a NAS and printer connect to the ethernet ports, and one ethernet port is connected to a Wifi Extender elsewhere in the house. There is 1 Subnet on this network (I also have an Airport that provides a Guest Wifi network, but not important to this story). The router gets IP config from my ISP via DHCP or similar, and this takes its configuration out of my control. Though I note that it does use One NZ's (my ISP) DNS servers. The local DHCP on the router for ethernet and Wifi is configured to provide the local routers IP address for DNS, and the router does pass through name resolution.

I do have a local DNS server too (a VMware ESXi host running a whole bunch of stuff for work, and it uses OpenDNS address for its DNS source) and it continued to work correctly. If I tried to configure my Mini to use it, it did not work. DNS Server logs showed no trace of activity from my Minis ethernet IP address.

The ethernet ports gets lowest cost route when both wifi and ethernet are connected, so once I connected the cable, DNS failed.

Oct 8, 2023 10:46 AM in response to Mista2

Yeah; this all reeks of an IP routing configuration error on the local network.


What happens outside the ISP router (or the ISP bridge, if you want to install your own router) wih DHCP and DNS and such typically isn’t central to these discussions. That either works or it doesn’t, and it’s the ISP’s problem to fix. Things get more interesting from the ISP router and its configuration and capabilities inward, or from the ISP bridge and your firewall / gateway / router / NAT box inward if so equipped and configured.


One potential cause here is the firmware of that router, and whether that can truly manage clients connected to both Wi-Fi and wired. If the Wi-Fi and wired networks are bridged at the router, that usually works. If not bridged (if routed), then the two network segments need to be in separate subnets to avoid getting routing tangled, or the clients cannot be connected to both.


Wi-Fi networks using routers with the same SSID are usually bridged, though each with a unique SSID usually gets its own subnet or potentially its own DMZ in these cases.


Here, use traceroute or ping from the malfunctioning client to the DNS server (to whichever of the various DNS servers is in use here) and then again traceroute or ping from that same DNS server to the client. TCP streams, and UDP requests and responses, sent to a server don’t necessarily use the same path to return packets from the server. They’ll use the least-cost route, which may not be the same physical path in each direction depending on costs and static routes and subnetting.


More generally, I’d be included to review and potentially to overhaul the whole network implementation, and probably to migrate from Wi-Fi routers to access points or mesh for the coverage, and either a DMZ or VLAN for the guest network.


Nov 29, 2023 1:36 PM in response to ciphershort12

I’ve seen DNS issues arising on every macOS version, and with pretty much every version of everything else everywhere. Usual DNS troubleshooting path is ping, traceroute, and checking the DHCP response from the DHCP server, and a look at the local network and its configuration. Recent Apple operating systems can also add ODoH, which also changes DNS behaviors.

DNS failure on Ethernet port only after Sonoma upgrade

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