Lose all connection from time to time

[assem_elgendy]

Hello Dears, 

I have the following LAN setup

- Fortigate 80E device with a port with LAN role, DHCP configured and connected to the lan side 

- 16 port Linksys unmanaged switch "Model lgs116"

- 5 D-link APs connected to the switch 

the problem is from time to time all LAN connection become down for about 5 minutes and up again, can't ping the fortigate device or any other device connected via wireless or wired connection, and this happens many times per day.

also I have noticed that when using a network devices discovery tool link "Fing" app, it causes the problem. but it happens with or without the using the app.

Any help ? 

Thanks in advance. 

[DevinderSharma]

Any chance there are two patch cables between unmanaged switch and the firewall? If so, please ensure that the STP / spanning tree protocol is enabled on the switch LAN ports of the firewall. I believe this should be on by default, but at least one thing that you can quickly verify.

Even if there is a single uplink cable from the linksys switch to the firewall, a short circuit downstream on the linksys switch ports will come upstream and result into loop type of situation. So I will check out the cabling as well.

[assem_elgendy]

Thanks for the reply, 

I'll check the linksys device and cabling.  

I'm operating with a normal port configured as LAN, Is there a difference between it and switch lan ports ?