I spent the whole day configuring the routers but no luck, my case as follow: I access internet through 4g huawi modem /router I want to connect wireless tp-link which connects two printers, I want to make the two networks connect and make the computers on the first network access the printer on the second network, as in the following diagram:
I need your advice on how to configure the routers.
To achieve this, the router on the second network needs to be configured to deliver IP addresses in the same subnet as the 4G router.
The easiest thing is to set the DHCP settings of the router to deliver IP addresses in an unused part of the network the the 4G router uses AND sets the default gateway to the 4G router and not itself. You will also need to make sure the DNS settings are consistent. So if the 4G router offers itself as the DNS server, make sure the other router also offers the 4G router as DNS server.
So if the 4G router is on 192.168.1.1, with its own DHCP service delivering from 192.168.1.100-150, the second router should have a fixed IP something like 192.168.1.10 and it's DHCP should deliver something like 192.168.1.200-250.
You also need to make sure that the second router allows all incoming traffic either by turning off it's firewall or by making 192.168.1.0/255.255.255.0 a straight passthrough.
UPDATE: If you cannot get your router to route on the same subnet. The alternative would be to move all client access to the router - though that does assume you don't have any problems with wireless reach. If you can do that, then you want to get the 4G router to have an internal IP address range such as 192.168.1.x, make the external address of the router a fixed address in that range and get the router to deliver DHCP on a different subnet such as 192.168.2.x
