AP Isolation

Don't under estimate the power of the Microsoft firewall to be a thorn in your side. I have been there and had that battle before. Ping the 192.168.12.1 gateway from both clients and then check the ARP tables each contains. Ping the broadcast address 192.168.12.255 and then check the ARP tables of each client again. 

If you use a third party internet protection suite that contains a firewall and other security features well that could be part of the equation as well.

These are printers that were working before on another gateway. But i will recheck once again and will post mY findings .

Thks

Ah! So look at the security on the printers. Check the WPA version. My Epson only supports WPA not WPA2 or WPA3 so in attempting to improve my security on the WIFI I set WPA2/WPA3 and knocked out the printer. You might have to adjust the security for the printers say on the 2.5 band to allow WPA.

Update while connected to thw gateway i can ping any thing on the .12 network but cant ping any thing on the .2 network.

While on the .2 network  i can ping everything on the gateway(.12 networ) and everything on the .2 network.

I turned of firewalls and still the same.

Imrouting 

Dest ip 192.168.12.1 /24 next hop 192.168.2.1 viq lan. 

Im confused

So "connected to the gateway"? You are referring to being on a client on the 192.168.12.x?24 network or what? My guess is the client obtains its routing information from the 192.168.12.1 gateway router. The gateway router will not have knowledge of the 192.168.2.x/24 network and there is no administrative right to add a static route to that segment on the Nokia router. Start with the client and if it is a Windows client issue the route print command. If you do not see the route there it has no way to get there. You can do a route add to the client(s) to inform it/them how to get to the 192.168.2.x/24 segment and what router to use as the interface to get there. You would need to add the -p to make it persistent or it would not remain after a reboot of the client. I am assuming this is a Windows client. You can do the same with Linux or Apple iOS. I forget the syntax nuances. I just look it up when I need it or check help/man files etc… 

Be sure to add the -p option to the command to make the route persistent

route -p ADD 192.168.2.0 MASK 255.255.255.0 192.168.12.200 <rtr interface?

After you complete the route add issue the route print command again. Keep in mind if you have the clients on the 192.168.2.x/24 segment with a router directing the traffic out to the internet via the 192.168.12.1 next hop router sure they can start conversations outbound. Nothing from the outside will be able to initiate a conversation with any of those clients as the GW router interface has no knowledge of that segment. 

All this makes the assumption:

192.168.2.x/24 NET--Rtr INT- Routing Device -Rtr INT--192.168.12.x/24--GW<192.168.12.1>

                                 (192.168.2.1)                    (192.168.12.xxx)

1rst why 192.168.2.200? Also I'm not using window clients nor linux I'm using regular CMD and router tools. From router .2 i can ping everything from router .12 i can pnly ping what is on that network can't even ping the gateway to the .2 network

please note that the .12 network is the nokia (t-mobile gateway).. I'm assuming its a t-mobile issue as it does not permit the wifi clienta to join a network rather than itself .

Out of ideaa

The 12.200 was an example. Please notice the >>192.168.12.200 <rtr interface? I am assuming you are using the ASUS to route to the 192.168.2.x network from the 192.168.12.x network.  You state "From router .2". It is not clear to me what you are doing. You need a router with two interfaces which has one in the 192.168.2.x/24 network and the other in the 192.168.12.x/24 network. A router with directly connected networks will be aware of both. The T-Mobile router has no way to know or be told that the other network exist without admin rights to provide the routing. If we could put a static route on the T-Mobile router to that network or use dynamic routing and run a routing protocol it would be possible but we don't have that luxury. Below ( 2 routers, yours with 2 interfaces & the Nokia with 1)

Is this what you have in effect? This is what you need. A router to pass traffic back and forth. The Nokia router will only ever send traffic to/from the GW interface between the local LAN and Internet.

192.168.2.x/24 NET--Rtr INT- Routing Device -Rtr INT--192.168.12.x/24--GW INT<192.168.12.1>

 Otra red               ^                   +                   ^     T-Mobile default network       +       ^

                             (192.168.2.1)    Router B    (192.168.12.???)  -------------------- GW router A

I am just using the bold print and underline etc… for emphasis and hopefully clarity. Again you must have the route statements on clients on the 192.168.12.x/24 network so they know what router to send the traffic they have destined for the 192.168.2.x/24 network segment. 

Maybe if you describe the actual connection(s) used to mate your network device to the Nokia router.

What type of physical interface are you connecting your network device to the Nokia router with? 

You previously stated, "Two devices on the same network which is on the gateway .12.x don't see each other." These were the two printers right? These were both connected via wireless connections? Did you get the printers visible? 

The problem as I understand it is you want to have two networks, 192.168.2.x/24 & 192.168.12.x/24.

If that is not what you are after then please define exactly what your objective is. If you want to use your own wireless device and allow it to switch to the Nokia router on the 192.168.12.x network then the clients would need to be on the same IP network. If you want some clients on the other layer three segment then a router is going to be required. We seem to have a disconnect as this is not rocket science. It is basic switching and routing. 

OK so early on you stated, “i tried to integrate my network con the device wifi clients and can't reach each other." Sorry I think I that part needs more definition. 

UNFORTUNATELY ITS THE GATEWAY ISSUE I WOBT LET ME SEE PAST THE GATEWAYS IP. THERE IS NO ROUTING OPTION. I CAN SEE EVERYTHING FROM MY HOME NETWORK BUT STILL CANT PING MY HOME NETWORK FROM THE WIFI NETWORK(GATEWAY). 

PLEASE HELP. 

ITS DEFINITLY A NOKIA RESTRICTION.

I take it that there is no solution to this problem. My Google Home products do not work. The error tells me to turn off AP Isolation. I finally get Internet in the house and can't use it for half of the devices that I use.