@database64128 requested issue #74737 to be considered for backport to the next 1.23 minor release.

@gopherbot please open backport issues.

In favor of backport:

1. The fix is simple and does not affect the path where it previously worked.

2. 52264 had a backport. Backporting this would ensure consistent behavior across both address families.

3. Having a failure mode like this makes WriteMsgUDPAddrPort harder to use right. The problem was discovered by a user under an unusual configuration. Having it backported would eliminate such edge cases that tend to be overlooked.

In opposition:

1. Because #52264 was fixed, this issue can be worked around by unmapping the destination address before calling WriteMsgUDPAddrPort.