WARP Client won't start if docker is running

When using docker desktop on MAC warp client fails to register.

Status: Unable to Connect
Error reason: DNS Proxy Failure
Error code: CF_DNS_PROXY_FAILURE
Error description: The WARP Agent must be the only process responsible for DNS resolution on the device. One or more processes are already bound to port 53: mDNSResponder.
Learn more: https://cfl.re/CF_DNS_PROXY_FAILURE

Workaround is to stop docker , start warp and docker after warp connects

System information:

      System Version: macOS 14.4 (23E214)
      Kernel Version: Darwin 23.4.0

Docker

      Docker version 25.0.3, build 4debf41

Another relative information i’ve found

When docker is running there is one process using port 53

➜  lsof -i4TCP:53                                                                                                                                                                                                 
COMMAND     PID           USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
mDNSRespo 59888 _mdnsresponder   30u  IPv4 0xe475b7215132aa9b      0t0  TCP *:domain (LISTEN)

When warp is running we have

➜  sudo lsof -i4TCP:53                                                                                                                                                                                                 
COMMAND   PID USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
Cloudflar 621 root   20u  IPv4 0xe475b721546eea9b      0t0  TCP warp-svc:domain (LISTEN)
Cloudflar 621 root   32u  IPv4 0xe475b72156749a1b      0t0  TCP warp-svc:domain (LISTEN)

i can start docker without issues after the WARP client connects but it won’t apear on the lsof

I’ve also found a similar issue with docker itself here that points to some apple virtualisation behave.

Thanks in advance

Perhaps this:

https://www.reddit.com/r/CloudFlare/comments/17wqajc/cloudflare_warp_is_not_working_on_mac_dns_proxy/

Thanks @cscharff ,
it worked.

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