Right my setup is as follows

TP-LINK AC1750 Wireless router

  • WAN (Comcast) connects here
  • 1 port connects to TP-LINK 16 port managed switch
  • 16 port switch has static IP, (I've reserved in wifi-router)
  • All PC's connected through the 16 port switch and pickup and IP from the router.

This is all working fine.

I have purchased a ZyWall VPN Firewall.

ZyWall VPN Firewall

  • 2 WAN ports
  • 4 LAN ports
  • The ZyWALL tries to assign IP's per LAN port. So 192.168.N.X, where N is the port # (1-4).

New Setup

  • WAN(Comcast) goes into WAN1 of ZyWall
  • LAN1 of ZyWall goes to a port (not the WAN port) on the Wifi router
  • Disabled DHCP on wifi router
  • LAN2 goes to a port on the TP-LInk 16 port managed switch
  • Everyone gets LAN ip's fine. All PC's connected to wifi router get 192.168.1.X IP's. All PC's connected to the 16 port switch get 192.168.2.X IP's


The internet seems to go in and out at random. Sometimes I can access it, other times I can't. I can ALWAYS access it if I plug a PC directly into a LAN port on the ZyWAll. It seems like if I wait long enough the internet will eventually completely cut out for any PC going through the Wifi router or the 16 port.

Any ideas? I've upgraded firmware to latest on all equipment.

  • What are you trying to acheive? Why did you purchase the ZyWall device? May 21, 2015 at 15:33
  • Well it was left over from a project someone gave it to me for free. I am running 6, xeon servers (each with 3 Ethernet ports, 2 LAN + IMPI). Off of these I'm running a lot of ESXi VM's. I will have about 4-6 users accessing the network via VPN. May 21, 2015 at 15:39
  • None of that constitutes to a reason to add another device to your network. Put another way, what is wrong with the TP-Link device you currently have? What new functionality do you need that the TP-Link router doesn't provide? If you can't genuinely answer that question, you don't need the other device. May 21, 2015 at 15:41
  • The TP-LINK AC1750 doesn't have built in VPN support. Maybe I could install DD-WRT on it? May 21, 2015 at 15:49

1 Answer 1


There is no reason why you would need to use both devices as routers, and I would strongly advise against running DD-WRT or any custom firmware in a work environment.

You need to pick one or the other and use that as your router, so assuming you use the ZyWall device:

  • Your Comcat WAN would connect to WAN1
  • Your switch would connecto to LAN1
  • Your PCs would connect to your switch ports

You'll need to reconfigure the IP address range of the ZyWall's LAN port, the switch (or both) so that everything is using the same network, subnet mask etc.

If you want to use the TP-Link device to provide Wifi, connect one of the TP-Link's LAN ports to a spare port on the switch or a port on the ZyWall (unsure if the LAN ports on the ZyWall can act as a switch - you may need to poke around the documentation or admin UI here).

This way, your Wifi clients will be using the same subnet as your PCs, which isn't technically recommended but would be fine for your small use-case.

Your other option is to purchase a standard Wifi access point - this would be much more straightforward than attempting to use a router as an access point (though it should by all means work).

  • Ok so I would turn off DHCP, and just assign a static IP to the wi-fi access point. May 21, 2015 at 16:03

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