Weird Spanning tree problem I can't figure out

[VirtualBacon]

I am having a weird spanning tree issue I've never seen before, and I can't wrap my head around

SW1 - Dell X1052P with STP enabled by default
SW2 - Cisco 2960-S with STP enabled by default

The switches are connected via a 10G Trunk, multiple VLAN's across it

I have a new TrueNAS system connected to SW1, the Dell X1052P. Its configured as an access port just like most other ports. When I turn off the TrueNAS box, all traffic to SW2 stops for a few moments, and LibreNMS reports an STP change. All of these are from me powering off the TrueNAS box for testing

I'm really not that up on spanning tree (I have a feeling I will be after this!)

Can anyone help shed some light how a link going on on switch 1 affects switch 2?

 

[legopc]

Tell us a little more about your current configuration and stuff like what flavor of STP you are using.

If I recall correctly with STP if there is a root bridge change all ports go back to blocking and sending BPDU's.