I have a network, which is 10.184.1.0/24. There is a hap2 managing it
I added a 2nd network 10.184.2.0/24 behind an old rb951.
rb951 is plugged into the 10.184.1.0 network via eth1 and has an IP of 10.184.1.90
Up until this point everything worked ok
I disabled masquerading for the traffic that goes from 10.184.2.0 to 10.184.1.0 as I want it to work both ways
I added a default route to the rb951 itself to go via 10.184.1.1 (hap2) jus tin case
I then added DHCP option 121 - 0x180ab8010ab80201000ab80101
option 3 - 0x0ab80101
options 6 - 0x08080808
I also set gateway and DNS in the DHCP network settings
I also tried option 121 to be 0x180ab8010ab80201 (i.e. without the 0.0.0.0)
I also tried every single combination of the above options
I also set the corresponding settings on the hap2, as in set a 121 option to route the traffic to 10.184.2.0 via 10.184.1.90
So the result is that both network see each other, but NONE of the network receive a default gw and a DNS if there is at least one custom DHCP option.
Once I remove DHCP custom options computers in 10.184.1.0 see internet but obviously not 10.184.2.0
Looks like custom DHCP options just breaks the whole thing.