bpdu-guard disables a port when it receives (unwanted) BPDUs. That is its design. You cannot use bpdu-guard with devices that you expect to emit BPDUs in general. The only way to keep bpdu-guard enabled productively is to make those device stop sending BPDUs.
If you want to ignore BPDUs from a port you should instead use bpdu-filter (ignoring BPDUs generally,...
server to Stratix loses connection for some seconds
(assuming layer-2 connectivity is lost)
MSTP is active but hasn't been configured sufficiently.
Likely, your problem is a combination of the missing root-guard, tcn-guard and portfast options.
You should at least
select a (central) switch as root bridge by settings its priority to 0 or 1 (or 0 / 4096 when ...
This configuration looks very much like a Cisco IOS configuration. You could try using the global spanning-tree portfast default global command. It only affects access interfaces, not trunk interfaces. Or, you could try the #spanning-tree portfast interface command for a specific access interface.
Portfast bypasses the STP blocking, listening, and learning ...