[release/10.0] [OSX] ip_mreqn struct is not supported for IPv4 Multicast #119480
      
        
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Backport of #119354 to release/10.0
/cc @liveans
Customer Impact
Running CI on latest macOS 26 showed a problem in IPv4 Multicast Interface. It is a regression against macOS 13.
Found internally via CI runs.
Regression
Technically yes -- due to different behavior of macOS Kernel -- since macOS 14 (see details above).
Testing
Failing CI tests now pass + manual testing of the Multicast Interface scenario (hard to automate).
Risk
Low, this was broken for a while since macOS 14.