Mysterious disconnects every 4 hours at specific times (e.g. 08:02, 12:02, 16:02 etc)

we have a real odd issue. Multiple users have noticed that their computers are unable to access various web and file based services at specific times 4 hours apart.

I've noticed the "disconnection" at 12.02pm myself and trying to access internal web based systems gives me a 404 page not found error. Others have noticed file shares becoming unavailable.

The outage lasts approximately 2 minutes each time.

We're running a 2 node Server 2019 hyper-v cluster with an infortrend SSD SAN backend and the services I describe are distributed across both nodes.

I've checked the host servers even logs, I checked the network switch logs and even some client event logs and nothing seems to correspond (or be anywhere near) to the time that the outage happens.

In tests we've run multiple Pings to hosts and VM's from endpoints to see if there is a network interruption but there isn't so much as a fluctuation in the MS response times. I realise Ping is a bit of a sledgehammer but given the duration of the outage I would expect to see something reflected but again nothing.

I'm at a complete loss so would be grateful for literally anything that might point me in the right direction.

thanks in advance,

Paul.

Right so turns out that the switch was recording a Syn Attack and shutting down the port for 60 seconds. The switches time was out so of course the attack didn't coincide.

The issue was / is caused by the spiceworks discovery scan. Since the syn attack settings are effectively causing a DOS I've switched them to report only mode.