How to merge 2 networks into 1?

Question

Computer networks

Hello! I have 2 local networks, 192.168.0.1 and 10.40.0.1, one is just a local network, the other is an internal document circulation in a secure network (via the Web). you need to merge these 2 networks into 1 so that you have access to both. there is a system unit with 3 network adapters, there is also a small mikrotik ... I don’t remember the model, and a l3 HP switch. I would like to somehow organize all this on this hardware. And of course safety is important!

Answer 1

If you want a software solution, then install pfsence.
But it will be better and more stable to consider the option of setting up routing between networks on the appropriate equipment. Switch L3 + ACL or Mikrotik + Firewall (for which there is enough money).

Answer 2

Do you have some kind of HP L3 switch? So do it on it. VLAN + ACL - for a start it will do, and then you can decide whether everything suits you and, if necessary, look after some other hardware, the same used l3 cisco, for example ...