@Mihau 

You are probably doing some heavy multicasting, but you do not control it. Just turning on RSTP will not solve that problem. Some configuration needs to be performed.

If you do multicasting, do you really need it? I have an NVR with 8 cameras connected to it. I played with multicasting in my surveillance VLAN a while ago. I got it working but, after a while, I realized that I do not really need it. Unicast is just fine for my use case and produces less traffic. I do not remember much from that exercise, but the lesson I’ve learnt is this. Multicasting from cameras to a NVR is not needed at all. Multicasting from an NVR makes sense only when you have many devices watching the video feed from it simultaneously.

  @Mihau 

Like in the previous post... turn off loop protection and turn on STP.  RSTP is STP on steroids.  Sometimes it fires off too quickly, STP usually plays happier.  

Since it's a dell… I'm sure it has an Intel NIC and Wi-Fi card. Go to Intel's site and download/install the newest drivers.  Windows Updates can be a tad behind in hardware/vendor updates.  Even update the BIOS on the dell machine.  

With that said... if the nic/wifi card is faulty, it can become "chatty" and blow up the errors logs in the switch.  Usually when this happens, STP fires off and blocks the port.  If STP isn't enabled, a L2 crash can happen.  Logs get filled, switch locks up/reboots, and it runs out of memory.  Which sounds like what is happening.  Updating firmware/bios usually can fix this.  If it's a known issue.... like I said, it maybe a fault NIC/wireless card.  Try a USB NIC / USB wireless dongle and see what happens.  

  @Mihau 

How a DNS setting of a single device can affect the whole network is beyond me. Maybe it is an IP conflict between your Dell and the router. Check the DHCP pool settings on your router and make sure it does not include the router’s IP address.