Unity unable to connect to network in certain cases

I am somewhat new to unity. I have been facing strange issues with my Unity.

1. I am able to connect to the asset store, search for items etc. but when it comes to downloading. It's stuck at 0 forever.
2. Other than that i am unable to collaboration services on my unity too.
3. Today i had worked on WWW module but the logs show an error saying "Cannot connect to destination host". There is no problem with the code as the same works for my colleague

I am not using any VPN or proxy. Google didn't help either. Tried on Unity 2019, 2018 and 2017. Same issue with all the versions. Some threads suggested deleting couple of asset store files. That didn't work too. The problem seems to be related to something else.