Hi zeeshan,
Please see the following Blog post for information about the DNS changes and whether you need to make any changes to your configuration:
http://www.sparklabs.com/blog/upcoming-dns-features-and-changes-in-viscosity-1-6/
If your connection works initially, but seems to stop after a few minutes, then try either unticking the “Enable DHCP” checkbox for your connection (under the General tab when editing your connection in Viscosity), or updating to the latest beta version. Instructions for enabling beta updates can be found at:
https://www.sparklabs.com/forum/t/beta-latest-build-of-viscosity-for-mac/46/1
Cheers,
James
