Late to the game but I see you need rescuing LOL
Assumes the management subnet is being sent to the MT as vlan and I am using vlan11.
Ether8 is not the managment subnet is the same subnet so taking this as an offbridge safe place to do the config etc.
DCHP client should be disabled!!
…
/interface bridge
add name=BR1 vlan-filtering=yes
/interface ethernet
set [ find default-name=ether7 ] comment=TRUNK
set [ find default-name=ether8 ] comment=OffBridge8
/interface vlan
add interface=BR1 name=vlanMGMT vlan-id=11
/interface list
add name=TRUSTED
/interface list-member
add interface=vlanMGMT list=TRUSTED
add interface=OffBridge8 list=TRUSTED
/port
set 0 name=serial0
set 1 name=serial1
/interface bridge port
add bridge=BR1 ingress-filtering=yes frame-types=admit-only-untagged-and-priority-tagged interface=\
ether1 pvid=10
add bridge=BR1 ingress-filtering=yes frame-types=admit-only-untagged-and-priority-tagged interface=\
ether2 pvid=10
add bridge=BR1 ingress-filtering=yes frame-types=admit-only-untagged-and-priority-tagged interface=\
ether3 pvid=20
add bridge=BR1 ingress-filtering=yes frame-types=admit-only-untagged-and-priority-tagged interface=\
ether4 pvid=20
add bridge=BR1 ingress-filtering=yes frame-types=admit-only-untagged-and-priority-tagged interface=\
ether5 pvid=30
add bridge=BR1 ingress-filtering=yes frame-types=admit-only-untagged-and-priority-tagged interface=\
ether6 pvid=30
add bridge=BR1 ingress-filtering=yes frame-types=admit-only-vlan-tagged interface=ether7 comment="trunk from Nonsense"
/ip neighbor discovery-settings
set discover-interface-list=TRUSTED
/interface bridge vlan
add bridge=BR1 tagged=ether7,BR1 vlan-ids=11
add bridge=BR1 tagged=ether7 untagged=ether1,ether2 vlan-ids=10
add bridge=BR1 tagged=ether7 untagged=ether3,ether4 vlan-ids=20
add bridge=BR1 tagged=ether7 untagged=ether5,ether6 vlan-ids=30
/ip dhcp-client
add interface=ether1 disable=yes
/ip address
add address=192.168.11.XX/24 interface=vlanMGMT network=192.168.11.0 { static IP from opensense }
add address=192.168.88.1/30 interface=OffBridge8 network=192.168.88.0 { use 192.168.88.2 for IPV4 settings to login with laptop }
/system identity
set name=MK-Pnet
/system note
set show-at-login=no
/system package update
set channel=development
/ip neighbor discovery-settings
set discover-interface-list=TRUSTED
/ip dns
set server=192.168.11.1
/ip route
dst-address=0.0.0.0/0 gateway=192.168.11.1
/tool mac-server
set allowed-interface-list=none
/tool mac-server mac-winbox
set allowed-interface-list=TRUSTED
/system ntp client
set enabled=yes mode=manycast
/system ntp client servers
add address=192.168.11.1