I have just installed Bitdefender 2017 having been using 2015 before that. I now find that computers on my network can't see each other and can't always ping each other. It seems to be inconsistent, so computer A can ping computer B, but B can't ping A, even though they appear to have the same settings in BD firewall. If I turn the firewall off, everything works, so it is clearly the Bitdefender firewall that is blocking.
All my adapters are set to the default - Home/Office - Off - Off. If I change to Trusted, then I can start to see other computers and everything works as expected.
So what is the difference between Home/Office and Trusted? The user guide is pretty useless on this, it just says
"Network Type - the type of network your computer is connected to."
Well that's helpful isn't it?
I don't remember having this issue with earlier BD version and I have been using it for years.