Sharing cable modem between 2 routers because of VPN service

[Honeymonkey]

I have a separate cable modem with dd-wrt router running open vpn. I pay a vpn provider for this service.

My problem I am looking for advise on is to share my cable modem between two routers so that all devices connected to the dd-wrt router to be protected by the vpn, and the other router can be using the IP my ISP provides and be in the clear. I have several cameras and other computers that are port forwarded so they can be accessed from the outside on the web. When they are behind the VPN of course, they cannot be accessed because those ports are not open, and cannot be configured by me.
My thinking is to run the modem into a switch or wired router, then plug the two routers into the wired router or switch.
I have read several posts on this, but none deal with the VPN.

So, I guess I have 2 questions.

1-will this switch or older 10/100 linksys router that runs directly off the modem slow down my 55 Mbps internet connection on the other 2 routers?

2- Since both modems don.t really need to talk to one another, can DHCP be active on both?

 

[bill001g]

You have to be very careful about your terminology. If what you have is just a cable modem you can only plug a single device into it....you can actually have more but the ISP want to charge for each IP they give you.

So you can't take a modem put a switch in front and then connect 2 routers.

Now if the device you call a modem actually has a router you can hook 2 routers to that. It would give you private address on the wan ports of each of these routers. You would then have 2 completely isolated networks. You could of course hook all your devices behind the modem/router and also your VPN router. This would mostly isolate the 2 networks depending on if you force the users behind the VPN router to only use the vpn or if they could get to the internet and you other network directly.

 

[Honeymonkey]

The cable modem is just that, a docsys3 modem without a router. So what you are saying is the only way to "split" the internet connection is to feed a separate router through the wan port, and then plug 2 routers into the ports.
This way the dd-wrt router running open vpn on port 1 can protect all devices connected to it with the VPN IP, and router 2 in port 2 can show all the devices connected to it the IP My ISP is providing allowing me to forward ports and connect from the outside to my cameras / computers.

If the above will work then my 2 questions still stand:

1-will the older 10/100 linksys router that runs directly off the modem that the other 2 routers are plugged into slow down my 55 Mbps internet connection on the other 2 routers?

2- Since both modems don.t really need to talk to one another, can DHCP be active on both?

 

[bill001g]

In general the 55m should cap the traffic before anything else but the port speed does not mean a lot about a routers ability to pass traffic. There are many routers with all gig ports that can only pass a couple hundred meg of traffic. If you router is very old it may have a cpu limitation that limits the traffic before you get to 55m. This is hard to actually find out rather than test.

If the networks are separate you can actually use duplicate IP addresses in addition to running DHCP.

 

[Honeymonkey]

Thank-you , just what I needed. So this you think is the best way to accomplish my port forwarding issues?

 

[bill001g]

It should work port forwarding is never easy when you have multiple routers involved it takes a lot of understanding how data flows but it will work just fine once you get it all figured out.