Hello,
I have a Linksys WRT1900AC with ChaosCalmer and an ethernet to SFP module connected to the WAN port of the router. This module is recommended by my ISP and confirmed to work by other user with various router but they don't provide the support to configure the router with OpenWRT (they guys at helpdesk is lost when I tell what options I have).

I have a current a router/modem ZyXel that work on this connection with the following configuration:

Mode: Routing
WANServiceType: IP over Ethernet
IPv6/4 mode: IPv4 only
VLAN
Enable VLAN: YES
Enter 802.1P Priority: 7 (but it works with any number I think)
Enter 802.1Q VLAN ID: 10
MTU: 1460
Obtain an IP address automatically: YES
Enable DHCP option 60: NO

Routing feature
NAT Enable: YES
Adress Mapping Enable: NO
IGMP Proxy Enable: NO
Apply as Default Gateway: YES

DNS
Obtain DNS info automatically: YES

6 to 4 tunneling: NO

How can I replicate this configuration in OpenWRT ?

It's the part where I have to enter VLAN ID = 10 that I'm not sure how to configure but I'm not even sure that the rest is correct to begin with. I have found a topic that seams to talk about a similar configuration but when I replicate what was explain it doesn't work and I have no ideas what is correct or not and what is not working exactly, the topic is this one: id=68206 (sorry no link allowed)

This will be a little different depending on which hardware version you have. 

Go to the switch configuration (Network --> Switch page) and change the VLAN number associated with the WAN port from 0 or 1 to number 10.  Change it from untagged to tagged on the physical port that goes to the modem cable (seems to always be port 4).

(Last edited by mk24 on 31 Mar 2017, 12:44)

First it was not working because I've messed up the interface configuration, but then I reset the configuration and did just what you did (in Switch, change the line VLAN 2 by 10 and tagged port 4), it worked immediately !!! Amazing how easy it is when you know what to do.
Thanks a thousand times, if you have a bitcoin address I'll send you some bits for a beer.

Now I have a long night re-configuring all the LAN network with my new router.

Hi all,
sorry for reviving an old post.
First of all, thanks for all the informations you already provided in this thread.

I'm going to move from an fttc connection to an ftth one, and i would like to keep my openwrt 1900acs on top of the chain.
Could you please provide me an example of the "ethernet to SFP module connected to the WAN port of the router" you used to make this work? Something like the tp-link FBA_MC210CS https://www.google.it/search?q=FBA_MC21 … p;ie=UTF-8??
I wish my isp's configuration will allow me to do the same as you did.
I think i'll need to clone the original router's mac address and find the vlanid for the wan interface
Thanks again,
K.

(Last edited by komodo_1 on 25 Mar 2018, 12:54)