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user_pgsewer
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Thursday, June 25th, 2026 5:34 PM

VPN Access using NAT

I am trying to configure VPN access to a LAN Server. I was hoping to setup NAT and Port Forwarding so that I could just leasve everything as is.

Is this possible, or do I need to set the Comcast modem into bridge or pass-through mode? 

If I have to setup the modem in this way, what then would I use for the routing and firewall?

Also, the Comcast Modem is the current wireless router, which I need to keep up as I do not have another wireless router on site.

Below is the equipment currently in use:

Comcast Modem CBR-T

Cisco VPN RV 325

Cisco Linksys E1000

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Comcast_Christy

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1 day ago

 

user_b09ed2 You may be able to get this working using port forwarding, but it can be inconsistent. Right now, your Comcast modem and your Cisco router are both acting as routers, which can cause issues with VPN connections.

The more reliable option is to put the Comcast modem into bridge mode. This turns off its routing so your Cisco RV325 can handle everything, including your VPN and firewall.

If you do that, the modem’s WiFi will turn off. To keep WiFi, you can use your Linksys router for that.

So in simple terms

  • Port forwarding might work, but may not be reliable
  • Bridge mode is the better option for VPN use
  • Cisco router handles the connection and security
  • Linksys router handles WiFi

Let me know if you want help walking through the setup.

 

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user_pgsewer

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@Comcast_Christy​

yes, can we please walk through this

I see the RV325 but it only has a public address, or so it seems

Can't I just use that address or is that the same address the Comcast Modem has?

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user_pgsewer

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Also, it looks like I cannot access the Linksys or the RV325 through their local IP Addresses

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Comcast_Christy

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56 Messages

 

You may be able to get this working with port forwarding, but it can be unreliable since both your Comcast modem and Cisco router are acting as routers. That setup often causes VPN issues.

For a more stable connection, the better option is to use bridge mode so your Cisco RV325 handles everything.

Recommended setup (bridge mode)

Step 1
Log into your Comcast modem (usually at 10.0.0.1) and enable Bridge Mode

Step 2
Connect an Ethernet cable from the modem to the WAN/Internet port on your Cisco RV325

Step 3
Restart both devices so the Cisco router pulls a public IP address

Step 4
Set up your VPN directly on the Cisco RV325

Step 5
Connect your Linksys E1000 to the Cisco router

  • Plug it into a LAN port
  • Set it to access point mode if possible
  • Use it for WiFi

Quick breakdown

  • Modem in bridge mode = no routing, no WiFi
  • Cisco RV325 = handles routing, firewall, VPN
  • Linksys = provides WiFi

If you’d rather not change settings, you can try port forwarding first, but if the VPN doesn’t stay connected, bridge mode is the fix.

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user_pgsewer

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Once this is done, should I be able to gain access to the RV325 and Linksys as to configure them?

If I need to turn the modem back into a router, how would I do that?
Also, should I save a backup of the current configuration of the modem, just in case?

And, can I change the wiFi on the Linksys to match the current WiFi from the Modem?

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Comcast_Christy

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56 Messages

ust want to make sure we’re aligned before you get started.
Once you enable bridge mode, your Comcast modem will stop handling WiFi and routing. Your Cisco RV325 will take over as the main router, and your Linksys will handle WiFi.
You’ll still be able to log into both the RV325 and the Linksys using their local IPs, so you can finish configuring them without any issues.
If you ever want to switch things back, you can log into the modem at 10.0.0.1 and turn bridge mode off to restore WiFi and routing.
I do recommend taking a quick screenshot of your current WiFi name and password before you start. You can use the same info on the Linksys so your devices reconnect automatically.
Give that a try and let me know how it goes or if anything feels off along the way.

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