I have spoken to DUCKDNS.ORG and this is their reply for those affected…
“Should be back now.
The original problem was a bug that caused high CPU.
However the fix for that has highlighted a dependency issue that has introduced a new memory leak.
we have revered the versions of some libs, this seems to have resolved that.
We are keeping an eye on it while looking for the library that has caused this.”
The High CPU, which made things intermittent.
However this mornings bug was a memory leak that was very obvious - after release the process ran up-to 26gb Virtual memory in a few seconds, then restarted (a feature).
We have put a work-around in place while we look or the root cause.