If I upgrade Webmin to the latest version through the System Information tool in Webmin some things start to break regarding the YubiRadius module.
Quote:
Webmin version 1.620 is now available, but you are running version 1.570.
* Simple things in the GUI like the tab bar gets looses its beveled edge and looks like broken css. Not important.
* When in the troubleshooting menu any test that is done and submitted sends you to the domain tab, clicking troubleshooting brings up the results. Rather annoying.
There might be other bugs that I have not noticed but I do not recommend upgrading Webmin, just to be safe.