How to ping to computer inside a sub network

Question

I have computer A and a router R1 connect to a main router R2, and computer B connect to router R1. The problem is from computer B, I can ping and connect to computer A but it cannot be reversed, i.e. computer A cannot ping to computer B.

What can I do so that computer A can see computer B?

Thank you!

Answer 1

If there is a working route between the computers, it sounds as if something else is going on - I would see if Computer B has a firewall and try disabling that... If it has Windows Vista/7/8/2008/2008 R2/2012, the firewall disables ping by default.