Thunderbolt interface vanishing from server when disconnecting the client

Hi everyone...here's the thing. I have a server running Openmediavault (a NAS interface for Debian) where I installed a Thunderbolt card. I configured the network interface, connected it directly to a MacBook via cable, bridged it, it works fine, I load the shares from the server via SMB, transfer super fast, everything works great. But...when I boot or turn off the Mac, or just disconnect the cable, the TB interface on the server disappears, and when I turn the Mac back on or reconnect the cable it doesn't reappear. I discovered that when I turn off the server (not just boot it up) the interface reappears and everything works again...any idea what this could be?
I'm lost here, and I don't want to keep turning the server on and off every time I close the Mac!
Thanks for any help!
Andre

BOLTCL shows:
boltctl info 19408780-00e3-286c-ffff-ffffffffffff
GIGABYTE GC-MAPLE RIDGE
type: host
name: GC-MAPLE RIDGE
vendor: GIGABYTE
uuid: 19408780-00e3-286c-ffff-ffffffffffff
dbus path: /org/freedesktop/bolt/devices/19408780_00e3_286c_ffff_ffffffffffff
generation: USB4
status: authorized
domain: 19408780-00e3-286c-ffff-ffffffffffff
parent: (null)
syspath: /sys/devices/pci0000:00/0000:00:1c.4/0000:06:00.0/0000:07:00.0/0000:08:00.0/domain0/0-0
authflags: none
authorized: Fri 09 Aug 2024 08:23:45 PM UTC
connected: Fri 09 Aug 2024 08:23:45 PM UTC
stored: no