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RT-AC68U router mode and port isolation

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Hey all,

I've been going through this forum (and also reddit lol) for the whole day. I've been banging my head on this for a while now, so decided to ask you wiser guys :).

I am running RT-AC68U in router mode with the newest AsusWRT-Merlin firmware (installed it today) and my WLAN is configured with Ruckus controller + AP's. My home network is pretty similar to every other; few smartphones/tablets, smart TV, HP printer, laptop and desktop PC. On top of that (which are probably not so common) I have a few IoT things scattered here and there (LAN and WLAN connections), and also a chinese CCTV system (NVR with 6 security cameras) behind a wireless mesh connection in another building.

I've run this combo for 7+ years but it has always bugged me, that all the devices are in my "main subnet" ( Now that I had some spare time I decided to look into this issue and thought it would be easy, but it wasn't (ofc not).

I can handle the WLAN IoT devices easily (I can isolate them from all other clients with my WLAN configuration), but I'd like to configure one (or two) physical ethernet ports on my RT-AC68U to another subnet (ie. This subnet must not have any access to the main subnet, but needs to access the internet.

I have the most basic idea how I would do that (for reference: https://wu.renjie.im/blog/network/ax88u-vlan/), but for the life of me I can only see eth0, eth1 and eth2 on my Asus with ifconfig, but robocfg showports shows ports 0-5, 7-8 (0=WAN, 1-4=LAN1-4, 5, 7-8=something related to WLAN). So I can't create a new bridge, which only has one physical ethernet port assigned to it.

How in the name of all that is holy can I manage to do this? :)


Maybe see the following discussions and see if anything there helps...

Otherwise do a search for robocfg, vlan and rt-ac68u to get a number of returns on past discussions.
Do not use this as a basis for your attempts. As Renjie points out, his AX88U (and the other HND routers) are completely different than the older models, like the RT-AC68U.

Look for existing posts on how to create custom VLANs using robocfg on the RT-AC68U.
Thanks for the tip :).

I've been going through this forum for quite a while but haven't stumbled upon a similar post.

One thing that bugs me is, do I need to use Jffs scripts or can I write the configuration to nvram?



Allright I had a little more time to look into this. I am sorry for my very noobish questions.. Now I got the hang of it, and I think I know how to do this.

I was able to get an IP address from the guest network range ( from my physical port 4 (commands: robocfg vlan 1 ports "1 2 3 5t" and robocfg vlan 501 ports "1t 2t 3t 4 5t"). And the network acted like a guest network (no access to home network, internet access working). So success, I guess? :)

This just isn't enough right now, because I need to be able to use DHCP and IP reservations for my camera and access point configuration. So I can't use the VLANs created by the guest network, but I do need to create a new VLAN and make a new bridge for it and some miscellaneous configuration. I've scoured this site (and also other sites) and have come up with this (which I will probably run as script services-start):

#create vlan100, tag it in port 4 and bring the vlan interface up
vconfig add eth0 100
robocfg vlan 100 ports "0t 4 5t"
ifconfig vlan100 up

#create bridge 100 and add vlan100 interface to it
brctl addbr br100
brctl stp br100 on
brctl addif br100 vlan100

#set ip address for br100 and bring it up
ifconfig br100 netmask
ifconfig br100 allmulti up

#configure nvram to allocate only vlan1 and wireless home network to br0
nvram set br0_ifname="br0"
nvram set lan_ifname="br0"
nvram set lan_ifnames="vlan1 eth1 eth2"
nvram set br0_ifnames="vlan1 eth1 eth2"

#configure nvram to allocate only vlan100 to br100
nvram set br1_ifname="br100"
nvram set lan1_ifname="br100"
nvram set lan1_ifnames="vlan100"
nvram set br1_ifnames="vlan100"

I have a feeling this is missing a lot of something, but it is a start. I know that I am missing at least routes and probably some firewall rules in iptables. The biggest issue I have, is that this RT-AC68U is up and running and I am very afraid to brick it (because wifey needs her Netflix and such). So that's the main reason I am taking this so carefully and I can't really test these configs anywhere else..

Hope this gives you guys a better view of what I want to achieve and how I might be able to get there.

Last edited:
And finally I was able to achieve what I needed by using @eibgrad's tutorial :). Why oh why I did not stumble in to this post earlier..

Actually I went ahead and created two new subnets, for ports 3 and 4. I might have use for the other one too. Now that I know how @eibgrad's script works, I may be able to configure my router without the script!

Default firewall rules in the script were wonderful. I have just a few little quirks here and there which I might need to look into, but so far this has worked like a charm for me :).

Thanks to you guys, and keep the flag high!


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