R1D2 wrote

Not your fault. Linksys does anything to confuse people, me thinks. According to OpenWRT's wiki about the Linksys WRT1xxx series the WRT1200ac has a Marvell 88E6176 switch:

https://wiki.openwrt.org/toh/linksys/wrt_ac_series#wrt1200ac

This switch uses following switch layout:

https://wiki.openwrt.org/toh/linksys/wrt_ac_series#marvell_88e6176



Quite right, but both WANs (WAN and WAN6 if you use IPv6) are using eth0 (the "Internet line" so to say).



Yes. The eth1 (without dot anything) is the physical interface designated to the 4-port switch. Ignore for a moment that the wiki page assigns this VLAN 1 in the wiki linked above (the "default" or "native" VLAN, actually for data packets without any VLAN ID). The "real" VLAN 1 is eth1.1 on top of eth1, but both interfaces co-exist.

The easiest way to get what you want is to do a factory reset of the OpenWRT firmware. Then note the network names, Ethernet interface names and WiFi interface names just to get an idea how this router is structured.

Next, create a GUEST network. If you also want a guest WiFi on the WRT1200 (beside the one propagated to the CPE), create another WiFi interface and assign it to the GUEST network. If you don't want a guest WiFi on the WRT1200, skip this step..

Then create a VLAN 2 ( eth1.2) and select this in the GUEST network settings to assign the network to this VLAN. Now add a port to VLAN 2 to have it carry data from the port into the GUEST network.

Do not change the existing eth0, eth1, eth1.1 settings, just expand it by creating a eth1.2. Use only the latter in individual settings except that you have to "move" the port for the CPE from LAN (eth1.1) to GUEST (eth1.2). Then it should work out of the box already.

It looks confusing because a) Linksys changed switch layout on their WRT series quite often and b) without doubt there is a learning curve in OpenWRT if you are new to it, but the more experience you get, the clearer things will become and at a certain point you will acknowledge to have a highly configurable firmware with lots of functions not even present in manufacturer's own firmware.

R1D2 wrote

Sorry, did forget this. Since OpenWRT's LuCI web UI uses a self-signed certificate with - meanwhile - weak signature algorithms, modern browsers refuse to accept it. Just ignore this. It's no bank account and no credit card data is at risk either. ;)

R1D2 wrote

Does not sound good. Now I understand what you meant with "script": did you insert a switch config manually? Usually the default config includes anything supported by the chip. If there is no VLAN section by default, this means that the chip probably does not support VLAN - that would be the first one crossing my way in more than 10 years work with OpenWRT, but everything is possible. My company changed the main supplier from Linksys to TP-Link after the WRT160 fiasco, shortly after Cisco took over Linksys. Seems it has been even worser with WRT1x00 family of routers ...

Let's see what the OpenWRT guys familiar with WRT1200 will say about it.

R1D2 wrote

Yes, the WNDR3700 will do it. I ported my OpenWRT-based software to the WNDR3800, which has the same architecture as the WNDR3700. OpenWRT firmware is identical for both models.

The WNDR3700/3800 have a Realtek RTL8366 Ethernet switch, which supports VLANs (see https://wiki.openwrt.org/toh/netgear/wndr3800#ethernet_switch_configuration_vlan).

I like this particular model b/c it has plenty of RAM and a fast CPU, at least for an embedded device released 6 years ago. Actually, it was once the premium model under a dozen of devices we offered customers until we introduced TL-WDR4300 some years ago. I still use my WNDR3800 beside several TL-WDR4300s.

No doubt, with the WNDR3700 you will achieve success in setting up a VLAN.