Router to Router OpenVPN with broadcasting/multicasting support

[dominatorstang]

My setup
Server Router - RT-AC56U dual core (Asus Merlin)
Client Routers - Routers supporting DDWRT, most do not support tomato and none support ASUS Merlin build

My goals:
-connect multiple routers over the internet using openVPN
-allow full client to client broadcasting and ip traffic
-keep things simple plug and play for client devices
-Each client internet traffic to go through their own local WAN
-Total devices on the network will be around 50
-all VPN traffic to work like the typical LAN with DLNA, Samba file sharing, RDC, etc..
-Each location to be served DHCP form its own router

I have tried a few different techniques and had issues with each. I want to make sure I work through the correct way of doing this to achieve the goals above using the correct configuration so I am not starting with the wrong setup and over processing and over complicating it into what I need.

Here is what I have tried so far with 1 DDWRT cleint router and each had success in some areas and issues in others

TAP on SAME subnet:
Worked the best so far but even with ebtables blocking DHCP then some devices still used internet traffic over VPN and I read ebtables is not efficient since it slows traffic by examining all traffic.

TAP on DIFFERENT subnets
did not get full traffic support between the two subnets but may have been some config issues. Internet traffic stayed local and I did not see DHCP traffic going through VPN (would have expected it too but maybe was still blocked from ebtables in above config)

TUN on DIFFERENT subnets
could not get broadcasting to work but seen information on wrapping it and sending it through which I have not tried yet.

If someone can help me decided of those 3 which is right for this setup or even one I have not tried yet. I can then show the config's, routing tables, and logs to see if someone cant point to me where I went wrong or what I need to add would be great

Thanks

 

[dominatorstang]

I have now put tomato on my RT-N53 client since I figure it will be setup more like the Merlin build on my RT-AC56U. I am using TAP on the same subnet and so far all is working out great. Still testing though. DDWRT OpenVPN just doesnt automatically setup things as well as the tomato and Merlin builds do from what I can tell. Most my other routers only support DDWRT though.