ADDITIONAL SYSTEM INFORMATION :
x64
Windows 7 / Windows 10
Java 8 Update 172

A DESCRIPTION OF THE PROBLEM :
Since Java 8 Update 172 all our JWS Applciations cannot be started from desktop anymore.

We get error: "System is offline"
In Details:

com.sun.deploy.net.FailedDownloadException: Ressource kann nicht heruntergeladen werden. System ist offline.
	at com.sun.deploy.cache.ResourceProviderImpl.checkUpdateAvailable(Unknown Source)
	at com.sun.deploy.cache.ResourceProviderImpl.isUpdateAvailable(Unknown Source)
	at com.sun.deploy.cache.ResourceProviderImpl.getResource(Unknown Source)
	at com.sun.deploy.cache.ResourceProviderImpl.getResource(Unknown Source)
	at com.sun.deploy.model.ResourceProvider.getResource(Unknown Source)
	at com.sun.javaws.security.JNLPSignedResourcesHelper.checkSignedResourcesHelper(Unknown Source)
	at com.sun.javaws.security.JNLPSignedResourcesHelper.checkSignedResources(Unknown Source)
	at com.sun.javaws.Launcher.prepareResources(Unknown Source)
	at com.sun.javaws.Launcher.prepareAllResources(Unknown Source)
	at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
	at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
	at com.sun.javaws.Launcher.launch(Unknown Source)
	at com.sun.javaws.Main.launchApp(Unknown Source)
	at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
	at com.sun.javaws.Main.access$000(Unknown Source)
	at com.sun.javaws.Main$1.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

Seems this problem was already fixed in the past:
https://www.oracle.com/search/results?cat=bugs&Ntk=S3&Ntt=System+is+offline
And with Update 171/172 several people seem to have this again:
https://stackoverflow.com/questions/1912676/i-am-not-able-launch-jnlp-applications-using-java-web-start

REGRESSION : Last worked in version 8u162

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Go to: https://wsvpruf-demo.dlz-it.de
2. Click on "WsvPruf mit Java Webstart starten"
3. End Application (IMS beenden)
4. Try to Open Shortcut "WSVPruf-QS 3.8.2 Demoversion" from Desktop

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Application opens
ACTUAL -
Error: "Application cannot be started, system is offline".



CUSTOMER SUBMITTED WORKAROUND :
Start applciation always from webpage.

FREQUENCY : always