After search, it's not possible on ipv4 but, on ipv6, i can add ‘next-hoop’ but i dont understand how configure properly ( jump to mk ipv6 routeur ?).
Hi @anav , i try and it’s work. I have some trouble with some device but i think it’s a prob with DNS resolver with dhcp.
I set DNS manually and i can acces on Internet.
I do more test soon.
"God, grant me the serenity to accept the things I cannot change, courage to change the things I can, and wisdom to know the difference"
For OP those things are:
- Router A
- The ISP
- The intention to isolate from the router dhcp and aspirations for how the system should work
For the rest of us, it is:
- just the OP
Can only assist when evidence is provided, anything else is speculation, aka the config! 
Yes for sure.
This is my /export (i don’t use firewall rules for filtering specific device)
/interface bridge
add admin-mac=XXXX auto-mac=no comment=defconf name=bridge
/interface list
add name=WAN
add name=LAN
/ip pool
add name=dhcp ranges=192.168.51.10-192.168.51.254
/ip dhcp-server
add address-pool=dhcp interface=bridge name=dhcp1
/interface bridge port
add bridge=bridge comment=defconf disabled=yes interface=ether1
add bridge=bridge comment=defconf interface=ether2
add bridge=bridge comment=defconf interface=ether3
add bridge=bridge comment=defconf interface=ether4
add bridge=bridge comment=defconf interface=ether5
add bridge=bridge comment=defconf interface=ether6
add bridge=bridge comment=defconf interface=ether7
add bridge=bridge comment=defconf interface=ether8
add bridge=bridge comment=defconf interface=ether9
add bridge=bridge comment=defconf interface=ether10
add bridge=bridge comment=defconf interface=ether11
add bridge=bridge comment=defconf interface=ether12
add bridge=bridge comment=defconf interface=ether13
add bridge=bridge comment=defconf interface=ether14
add bridge=bridge comment=defconf interface=ether15
add bridge=bridge comment=defconf interface=ether16
add bridge=bridge comment=defconf interface=ether17
add bridge=bridge comment=defconf interface=ether18
add bridge=bridge comment=defconf interface=ether19
add bridge=bridge comment=defconf interface=ether20
add bridge=bridge comment=defconf interface=ether21
add bridge=bridge comment=defconf interface=ether22
add bridge=bridge comment=defconf interface=ether23
add bridge=bridge comment=defconf interface=ether24
add bridge=bridge comment=defconf interface=sfp-sfpplus1
add bridge=bridge comment=defconf interface=sfp-sfpplus2
/ip neighbor discovery-settings
set discover-interface-list=LAN
/interface list member
add interface=ether1 list=WAN
add interface=bridge list=LAN
/ip address
add address=192.168.51.1/24 interface=bridge network=192.168.51.0
/ip dhcp-client
add interface=ether1
/ip dhcp-server network
add address=192.168.51.0/24 dns-server=192.168.51.1 domain=local.local
gateway=192.168.51.1 netmask=24
/ip firewall filter
add action=accept chain=input connection-state=established,related,untracked
add action=drop chain=input connection-state=invalid
add action=accept chain=input comment="defconf: accept ICMP" protocol=icmp
add action=accept chain=input dst-address=127.0.0.1 in-interface=lo
src-address=127.0.0.1
add action=accept chain=input in-interface-list=LAN
add action=drop chain=input comment="drop all else"
add action=fasttrack-connection chain=forward connection-state=
established,related
add action=accept chain=forward connection-state=established,related,untracked
add action=drop chain=forward connection-state=invalid
add action=accept chain=forward comment=internet in-interface-list=LAN
out-interface-list=WAN
add action=drop chain=forward comment="drop all else"
/ip firewall nat
add action=masquerade chain=srcnat out-interface-list=WAN
/system clock
set time-zone-name=Europe/Paris
/system routerboard settings
set enter-setup-on=delete-key
/tool mac-server
set allowed-interface-list=none
/tool mac-server mac-winbox
set allowed-interface-list=LAN
With a device on this network (IP and DNS from MK DHCP) (sorry, French user)
tracert www.google.com
Impossible de résoudre le nom du système cible www.google.com.
Adding DNS to 8.8.8.8 on this device
tracert www.google.com
Détermination de l’itinéraire vers www.google.com [172.217.22.4]
avec un maximum de 30 sauts :1 <1 ms <1 ms <1 ms 192.168.51.1
2 1 ms 1 ms 1 ms 192.168.1.254
Well sorry it’s ok …
I change DNS from DHCP Server part and it’s OK (default to 192.168.51.1 :/)
Thanks @anav and all others for help !