We are having a issues with multiple devices on our network not being able to connect to the Internet but can get to network shared, deivices, etc. It started with two servers have issues and now we have random desktops, laptops, servers, and even WAP's having Internet issues.
When a computer cannot get out to the internet we check the ARP cache by going to cmd prompt arp -a and notice that the firewall is either not listed or says invalid. When we manually enter the ARP entry for the firewall internet is restored immediately.
SonicWall Pro 3060 firewalls (two- both have ARP issues one more than the other, DHCP and VPN on firewall)
D-link- switch- had collisions on one port
two netgear and a linksys.
One company recommended that the switch be replaced. We replaced the switch with a brand new HP switch, plugged both firewalls and all servers and switches directly into the new switch and still had the ARP issue. See attachment for further troubleshooting we have done.
SonicWall technical support recommended we upgrade the firmware on the firewall because it may be causing the issue. Any other input would be greatly appreciated.