How to change value of 'Read timeout' of Eclipse's Update Manager?

As Frank mentioned you can set the timeout options in the eclipse.ini, here's the documentation.

"use -DpropName=propValue as a VM argument to the Java VM, set the desired property in the config.ini file in the appropriate configuration area"

I set the following to get round my timeout issue:

-Dorg.eclipse.ecf.provider.filetransfer.retrieve.closeTimeout=3000
-Dorg.eclipse.ecf.provider.filetransfer.retrieve.readTimeout=3000

I got the error a lot with version 3.6, but adding the following line to the eclipse.ini helped me a lot:

-Dsun.net.client.defaultReadTimeout=30000

Add it right after the line with -vmargs