@David-TP Sorry, cannot do this.

The main Deco is on floor2, where the internet wire is incoming, and the extra LAN is outgoing to my neighbor.

The secondary Deco is on floor1 (the living room), and I cannot easily run wire between my two floors.

 

BTW, a couple days ago I left an older D-Link router instead of the Archer A5.

Now the Deco management app says it's successfully connected (to the main Deco)!

 

I think it should be some simple configuration, to tell the Archer which IP range to use for its subnetwork?

 

  @VladimirAlexiev 

 

Fast and raw answer with IPv4 : do "dual NAT". One NAT in your master deco, one NAT on the archer. Keep network numbering clearly separated to get it simple : one on 10.0.0.0/8, one on 192.168.xx.0/24 for example. Easy but quite a lot under-optimal. It is time, and cpu consuming on each router.

 

To complicate with IPv4 : you can do routing between network IPs. you need to manually set  the network IP for inner and outer network on each router then set static routes on both routers or simply set automatic routes with RIP or OSPF enabled : routers will communicate with each others while you'll be sipping your coffee.

 

To get it simple with IPv6 : try to do routing with prefix delegation between the routers. If the DECO is able to do that as any IPv6 router shall be able to : it will be plug&play. you need to allow DHCPv6 server on DECO and a DHCPv6 client on Archer tuned for asking for a prefix. As there is no NAT, nor no private address like IPv4 on IPv6 : it is a little bit different to manage but it is fully automatic. If you use private address like fd00::/8 you will not be routed off your home, i'm not sure you want that. if you use general address (2000::/3) from your ISP and do subnetting suing /64 for example, you'll better do prefix-delegation as intended by IPv6 norms.  If you've got several routers behind a head router, you can do static routing but this is taking the hammer out to slap a fly ! You can also set RIPv6 or OSPFv6 to share and set routes automatically. Additionally as any interface can own as many IPv6 addresses you wish, you can set a global address (2000::/3) and local address (fd00://8) and the mandatory local link address (FE80::/10) on each interface. This way your network will remain functional if you loose your ISP link and will be automatically fully restored when available through delegation.

 

And there's the dummy configuration with two entities : configure your archer as bridge (no router) + wifi. but you must understand that security is all in your hands.

  @David-TP I attached an old D-Link router to the main Deco and it worked like a charm for a week:

Then the connection became unstable and after restarting the D-Link, it cannot connect anymore:

As for the Archer, it can never connect (except for maybe a day, a month ago). See the WAN section below:

Here's the WAN config on the Archer:

@Eric_Le_Grompf Thanks a lot for your advice!

It's complicated for me: although I'm in IT, my networking knowledge is rather basic.

Before trying to implement it, could you please take a look at my previous posting (with the shots from D-Link and Archer): what I don't understand is how come D-Link worked for a week, and now it doesn't work.

I'll wait a bit for an answer from David-TP or another TP staff, and if nothing comes in, I'll try to follow your advice.

 

Failing this, I can buy another pair of Decos and use "ethernet backhaul". But it's a pity to throw away a perfect Archer A5...

Given that both Deco and Archer are TP products, they should talk to each other without problems!

  @VladimirAlexiev 

 

OKAY, through your last post i see a better picture of it. It seem to be at a lower level than i firstly expected. There's not established physical link.

 

first DECO and Archer are using two different wifi technology MESH and WIFI ARCHITECTURE. The last one uses one central powerful access point. They are not mixable or you'll need an archer compatible with DECO protocols (i don't know if it exists)

 

Two archers can do what you want to do simply by configuring them as WBS bridge (one normal mode of "architecture mode") tied to each other to create a private point to point back haul link. Depending on router's design you may loose the AP function for local client or not.

 

On their side DECOs expect a WiFi client to connect over the available wifi network not on the back haul link. No AP can connect on the back haul link. It means that either your Archer or your Dlink cannot connect to DECO network if configured in AP mode ou Router mode. Your temporary exception looks like the detection of a bug in the firmware of one of the unit.

 

First, i believe, you need to fix the wifi link then if there's routing problem : escalate to IPv4/IPv6 level as i mentioned.

For this, you need to switch your archer setting from router to client mode, and to set it to connect to the client wifi network from DECOs. (don't forget to renew all your IPs on archer side). You'll loose the wifi AP function on the archer and the routing function too i suppose as it will behave as a wifi client with a switch.

 

Note : if your router is set to channel auto-select  at the next reboot its access point will jump to another channel if it detects another forgeign access point on the current channel. 

@Eric_Le_Grompf 

• Previously the D-Link (in my house: primary) and the Archer (in friend's house: secondary) worked without any problem, each providing WiFi in the respective house
• There's no WiFi interference between the two houses because they're far enough from each other
• Deco can use the LAN port either for ethernet back-haul, or to attach a client:
  • My secondary Deco has a TV set-top box attached through LAN
  • A laptop at friend's house attached to the LAN (in place of the Archer) works fine
• What really puzzles me why the D-Link (at friend's house) worked fine for a week, but now it cannot connect
• Even the Archer connected for a day (that was a month ago), now it cannot connect
• It almost feels like a Deco firmware upgrade has caused it to refuse connection from other routers!

 

I've tried the Archer in AP mode (not Router mode), but still no cigar :-(

Sorry, which options do you mean? I mean this terziyski : https://community.tp-link.com/en/home/uc/info/991492 . But I don't think there's a way to ping someone, unless you Reply to his message. Cheers!