Why can't I access website nest.com with Safari on my MacBook Pro?

My system configuration:

Late 2013 13" Retina MacBook Pro, MacOS 10.13.4, 16 GB RAM

All apps at their current revisions

I discovered recently, in about last 4-6 weeks that I cannot access URL nest.com using either Safari or Chrome web browsers. I have confirmed that my UID and PW are correct because I am able to connect to Nest app on my iPhone and I can access Nest.com using any browser on a Windows 10 laptop.

No other websites see to be affected. I am able to access all other websites that I customarily access.

Only change I can think of is that I replaced my previous Anti Virus program with Kaspersky Internet Security app.

I will appreciate any clues you can give to investigate the problemm

Thank you.