Hello everyone!

I am relatively new to this forum, and wanted to get some useful feedbacks and resolution from "network-PROs" on my problem..

I have a network with a main router connected to the Fortigate Firewall 100E, that is connected to a Cisco SG300-28PP 28-Port Gigabit PoE+ Managed Switch through which all the user computers and IP phones are connected.

Lately, time-to-time, out of no-where, the internet keeps disconnecting. From the LAN, I'm unable to access the firewall and its unreachable. The WiFi from the main router works fine, that means the Internet is okay. After restarting the firewall physically, everything is back to normal and the internet runs fine.. I have checked the switch, and it shows no sign of problem in any way!

I don't know if its the problem of the firewall or the switch. Hope someone can guide me to the right direction.

Logs from the Fortinet

That power supply lost is from the time, when I had to restart the Firewall from the switch, since it was inaccessible.

P.S: I have been seeing this logs about Link-up and Link-down for the WAN.. The same problem hasn't happened yet. I have also restarted the CISCO Switch couple of days back, since then, there is no problem.

closed as too broad by Ron Maupin Dec 31 '18 at 21:50

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Both the firewall and the switch have logging features. Look at the logs of both devices for some clues as to what's wrong. I'm most suspicious of the firewall. – Ron Trunk Jul 1 '18 at 11:38
  • If you can't reach the firewall it's not the Internet uplink that's failing... – Zac67 Jul 1 '18 at 12:56
  • when this occurs, is there any port flap on the switch? Is it possible to send equipment logs? The firewall you have access to it remotely to verify when this problem happens, if the firewall still has internet? if it works, you can already eliminate it and focus on the switch. I await logs – Pedro Ferreira Jul 1 '18 at 19:53
  • @RonTrunk I have posted below the screenshot of the Fortinet log.. As for the Cisco Switch, its totally blank.. or maybe I'm checking in the wrong place.. – 3mmaar Jul 3 '18 at 6:35
  • @PedroFerreira - I'm unsure of the concept 'port flap'.. The firewall is inaccessible when this problem happens, even if you connect to the LAN of the firewall.. – 3mmaar Jul 3 '18 at 6:41