That post applies, is the same situation (I didn’t take ISP router into account).
You should either:
a) Put ISP router in “bridge mode” and setup one of the Haps (say Hap A) as your main router: it will get the public address, run the LAN DHCP server, firewall, etc.
You must reset it to defaults and may use Quick set to set it up as Home AP. The LAN address block that you assign here will be the one used on all your network.
On Hap B, you’ll have to reset to no defaults, and use winbox to carry out the configuration steps on by yourself without using Quick Set:
1.- Reset it to no defaults
2.- On Interfaces > ethernet ether2,3,4,5 general tab set ether1 as master port
3.- On Bridge > Bridge Create a bridge, go to Ports tab and add ether1, and wlan1 to it
4.- Configure wireless (wlan1). Use a different non-overlapping channel, e.g. 6 if you used 1 on Hap A
5.- Assign an ip to the bridge (only needed to manage it by ip, you can manage it without ip through mac-winbox or RoMON)
Connect ether1 from Hap B to any ether port belonging to the bridge where DHCP runs on the main Hap A router.
You can use any ether port on the Hap B as all are bridged, but ether1 is the one used as is usually directly connected to the CPU on most routerboards.
With this what you have setup on Hap B is basically a pure Layer 2 AP/switch, which “extends” your main router Hap A layer2 segment.
b) Leave ISP router as is, and configure both Haps as pure Layer2 “AP/switches” (like Hap B), connecting them to the ISP router.
On step 5, if you want to manage them by IP, instead of assigning an IP manually on the bridge you could add an IP > DHCP client to it so that both Hap get IPs (used only to manage them) automatically; make both as “static DHCP leases” on your ISP router so that they always get the same.
I usually advise option a, leaving the ISP router as an “*DSL ISP adapter”, as most are crap (Thomson Technicolor tg582n belonging to this category), and will perform much better this way.
