How to set up the correct routes?

Question

System administration

Good afternoon! There is Internet access via adsl modem tp-link 192.168.1.0/24. We want to separate one department from the general network and give them access to the Internet. We found zyxel keenetic 2. In the WAN port we connected a cable from the network 192.168.1.0/24 to zyxel we use the network 192.168.5.0/24. Everything is set up for clients with zyxel. DHCP works as it should. Now the actual problem is that clients from the 192.168.5.0/24 network see clients on the 192.168.1.0/24 network, which shouldn't happen. Useful in zyxel found the routes that he himself set up. Tell me which ones to remove so that there is no access to the network 192.168.1.0/24, but the clients of the network 192.168.5.0/24 still have access to the Internet. Thank you!

You can add or remove a route only from "Static routes"

Answer 1

This is not handled by routing.
Try to configure the firewall on the tp-link so that it does not allow packets from 192.168.5 to 192.168.1 and vice versa, except for your own tp-link address (otherwise everything will fall off for you for 192.168.5).

Answer 2

well, if you do it with routes, then you need to send all addresses from the 192.168.1.0/24 grid except 192.168.1.1 to a non-existent gateway, i.e. these are networks:
192.168.1.2/31
192.168.1.4/30
192.168.1.8/29
192.168.1.16/28
192.168.1.32/27
192.168.1.64/26
192.168.1.128/25
or, more correctly, must be configured on the TP link a firewall that will prohibit everything in the destination from entering these networks, or set up access to these networks on the zuksel