hi everyone

I am having a bit of an issue with my RBwAPG-5HacT2HnD AP. neither DHCP server or DHCP relay are enabled. I just need a dumb AP plugged into the LAN.

my DHCP server is the same as my router, on the same LAN. I have a WiFi client connected to the MT AP, running a bridge (OpenWRT/relayd) to extend my LAN via WiFi.

when a DHCP DISCOVER/REQUEST is sent from the extended part of the LAN, it makes it to the DHCP server unchanged. so far so good.
however, when the DHCP OFFER/ACK comes back via the MT AP into the WiFi client, the destination Ethernet address is replaced from broadcast to the unicast address of the client's WiFi interface.

the DHCP Broadcast is always set in both requests and responses. despite that the Ethernet destination address change happens. this is where I think the MT AP is breaking standards, however my goal is to make it stop substituting addresses altogether.

I tried temporarily replacing the MT AP with an arbitrary AP and everything works (Ethernet destination address remains broadcast).

is there a configuration option that is responsible for this behaviour?

thanks in advance for any explanations and suggestions.

Login with Winbox to your AP.
Open a terminal and paste: Paste the content of that file here

[admin@MikroTik] > export compact hide-sensitive
# feb/04/2020 15:40:05 by RouterOS 6.44.2
# software id = E7WN-J2XK
#
# model = RouterBOARD wAP G-5HacT2HnD
# serial number = 7DF308E606B8
/interface bridge
add comment=defconf name=bridge
/interface wireless
set [ find default-name=wlan1 ] antenna-gain=2 band=2ghz-b/g/n channel-width=20/40mhz-Ce country="united kingdom" disabled=no distance=indoors frequency=auto \
frequency-mode=regulatory-domain mode=ap-bridge ssid=n0nesuch_2 wireless-protocol=802.11 wps-mode=disabled
set [ find default-name=wlan2 ] antenna-gain=2 band=5ghz-a/n/ac channel-width=20/40/80mhz-eeCe country="united kingdom" disabled=no frequency=5300 \
frequency-mode=regulatory-domain mode=ap-bridge ssid=n0nesuch_5 wds-default-bridge=bridge wireless-protocol=802.11 wps-mode=disabled
/interface ethernet
set [ find default-name=ether1 ] speed=100Mbps
/interface list
add comment=defconf name=WAN
add comment=defconf name=LAN
/interface wireless security-profiles
set [ find default=yes ] authentication-types=wpa-psk,wpa2-psk mode=dynamic-keys supplicant-identity=MikroTik
/ip hotspot profile
set [ find default=yes ] html-directory=flash/hotspot
/ip pool
add name=dhcp ranges=192.168.100.85-192.168.100.90
/ip dhcp-server
add address-pool=dhcp interface=bridge name=defconf
/interface bridge port
add bridge=bridge comment=defconf interface=wlan1
add bridge=bridge comment=defconf interface=wlan2
add bridge=bridge interface=ether1
/interface list member
add comment=defconf interface=bridge list=LAN
/ip address
add address=192.168.100.80/24 comment=defconf interface=wlan2 network=192.168.100.0
/ip dhcp-client
add comment=defconf dhcp-options=hostname,clientid disabled=no interface=bridge
/ip dhcp-relay
add add-relay-info=yes dhcp-server=192.168.100.128 interface=wlan2 local-address=192.168.100.80 name=relay1 relay-info-remote-id=""
/ip dhcp-server network
add address=192.168.100.0/24 comment=defconf dns-server=192.168.100.128 gateway=192.168.100.128 netmask=24
/ip dns
set allow-remote-requests=yes servers=192.168.100.128
/ip dns static
add address=192.168.100.80 name=router.lan
/ip firewall filter
add action=accept chain=forward comment="defconf: accept in ipsec policy" ipsec-policy=in,ipsec
add action=accept chain=forward comment="defconf: accept out ipsec policy" ipsec-policy=out,ipsec
add action=fasttrack-connection chain=forward comment="defconf: fasttrack" connection-state=established,related
add action=accept chain=forward comment="defconf: accept established,related, untracked" connection-state=established,related,untracked
add action=drop chain=forward comment="defconf: drop invalid" connection-state=invalid
add action=drop chain=forward comment="defconf: drop all from WAN not DSTNATed" connection-nat-state=!dstnat connection-state=new in-interface-list=WAN
/ip firewall nat
add action=masquerade chain=srcnat comment="defconf: masquerade" disabled=yes ipsec-policy=out,none out-interface-list=WAN
/system clock
set time-zone-name=Europe/London