1、Open Eclipse->help->eclipse marketplace error
Cannot open Eclipse Marketplace
Cannot install remote marketplace locations: Connection failed
This is most often caused by a problem with your internet connection. Please check your internet connection and retry.
Unable to read repository athttp://marketplace.eclipse.org/catalogs/api/p.
Connection reset
Connection failed
This is most often caused by a problem with your internet connection. Please check your internet connection and retry.
Connection reset
How to Fix
(1) window->preferences->General->Network Connections，Active Provider Click Manual
(2)Add  -Djava.net.preferIPv4Stack=true in eclipse. ini