Spiceworks can't connect to some of the computers via WMI

What:

Spiceworks installed on Windows 7

Problem:

We couldn't connect to this device due to the following error: No open ports for this device were found to be responding.

Solution:

Follow the steps from the link below, make sure your firewall is not blocking the connection.

http://community.spiceworks.com/help/Inventory_WMI

If you still have the same error message, then that could be problem with your PTR records.

Test it with nslookup:
1. Start > Run > cmd.exe
2. Start nslookup

nslookup

 type in name of the pc, A record check

> workstation1
Name: workstation1.domain.local
Address: 192.168.1.50

 type in IP of the pc, PTR record check

> 192.168.1.50
Name: workstation1.domain.local
Address: 192.168.1.50

They both should resolve to the same name, if not you need to clear stale records and best reconfigure DHCP server to handle all records correctly.

Related post:
Revers DNS entries are not updating, Windows 2012 R2