Your logs for the red interface don’t show any problem there.
Your openvpn authentication executable was killed because your system ran out of memory. What does the Memory WUI menu item show for the usage and especially around the time that you had the problem. Either you are running very close to using all the memory up on an ongoing basis, or some program executed and used up all the memory and had a higher priority than the openvpn authentication program.
There are also quite a lot of I/O error which doesn’t look good.
What does the SMART status from the WUI Status - Media menu item say about the disk drive.
Your summary log would make me look at potential hardware problems. That would also tie up with the collectd messages about many values being too old. It is not getting any new data and the cache data is too old My first thought on that was that there was a problem getting the required data for the rrdtool to put into the graphs.
The collectd error messages could also mean that you don’t have any memory data in the graphs for the time that the problem happened.