Comment 67 for bug 1711407

> Hi, might be useful to find root-cause

"root-cause" for this is a dst object leak, and there have been many kernel dst leak patches, there almost certainly are still dst leak(s) in the kernel, and more dst leaks will be accidentally added later. Unfortunately, the dst leaks all lead to an identical end, with the 'waiting for...' error message printing in a loop, and blocking creation of new net namespaces. So, there is no single "root cause" for this. Disabling ipv6 may help in your situation, and may help others as well, but will not work for everyone.