I have a Cisco 4506 with a Soup 3, A Fortigate 80C, and a Cisco UC500 with about 15 phones. There are two Vlans, vlan1 "data" and vlan100 "voice". All the phones work fine and computers are able to access local network resources. All the computers connect to a cisco ip phone which is gets POE from the 4506. The problems start when a computer trys to access the internet. Computers will randomly access the internet one minute then the next they can't. For example the computer I am on now has internet access but the one next to me does not. I will refer to my computer as computer "A" and the one next to me as computer "B". Computer B can access any local network resource but cannot ping the router or access the internet. So afew minutes pass now computer A cannot access the internet but computer B can. This is very confusing. Does anyone have any ideas as to what could be causing this?
Thank you for you time.