Not sure if this will work (as encryption is not set):
/interface wifi security
add authentication-types=wpa2-psk,wpa3-psk disabled=no encryption="" name=sec-home
Why the hidden SSID?
/interface wifi configuration
add comment=Dummy disabled=no hide-ssid=yes mode=ap name=Dummy security=sec-home ssid=dummy
Don't set VLAN ID 1 explicitely:
/interface bridge vlan
add bridge=bridge comment=Management tagged=ether3-Router-7,ether2-Router8,sfp-sfpplus1-Backbone,sfp-sfpplus2-Server untagged bridge,ether4,ether5,ether6,ether7,ether8 vlan-ids=1
My best guess would be that the VLAN part of your config is incorrect.
Can you share /interface for both router and accesspoint?
For reference: