Region : Romania

Model : TL-ER6120

Hardware Version : V1

Firmware Version :

ISP :

Hello everybody,
Please help me with the following problem:
I am trying to configure an additional small network for printers, inside the main network.

The primary network setup:
10.100.100.1
255.255.255.0

I have connected the TP-link router, to an existing network, with the following settings:
WAN:
IP: 10.100.100.159 (static IP with reservation)
Subnet mask: 255.155.155.0
Gateway: 10.100.100.1
LAN:
IP: 10.100.155.1
Subnet mask: 255.155.155.0

From the main network, I can ping the router (10.100.155.1), but I cannot ping or access any of the devices connected on LAN (10.100.155.2 - 10.100.155.254).
The other way, everything works fine, from the 10.100.155.x network I can ping and access any of the 10.100.100.x computers.
I disabled all firewalls, both on router and LAN PC.

Thank you!