2nd LAN interface issue

[Daemotrix]

Hi,
I have a problem. My FW is running on one builtin NIC system (assigned for WAN) so I'm using USB LAN adapter (assigned for LAN) and I need to add one more USB NIC. 1st is configured as
IP address 192.168.1.1/30 so the other side (WiFi router) has IP 192.168.1.2 and connection works perfectly. But if I connect 2nd adapter so I set 192.168.1.4 and the other side 192.168.1.5, so connection stops working on both interfaces and I'm unable to access to the internet. Can you anybody help me please, ho I must configure that interfaces correctly?

[Sirius1]

Assuming you are also using another /30, your 2 hosts should be .5 and .6. Broadcast address will be .7.
The .4 is the next available subnet.

[Daemotrix]

I tried .5 with mask /27 but still without success

[Sirius1]

I think you're complicating the issue by trying to use the 'sequential' addresses you're using, and mixing masking.

A '.5' address with a /27 mask is going to assume that everything from .1 to .30 is part of the same subnet. Your masking and subnets are then overlapping. You'd probably be much better off using a different network range and  mask for your new interface.

Your options are: 1) choose a different network like 192.168.2.0 with whatever masking you want, or 2) need to go to 192.168.1.33/27 which would be the next valid IP to use with a /27 and keeping your 192.168.1.x addressing.

If you are trying to do a more complex setup, you need to have a better grasp of IP addressing and masking. Use an online calculator to show you valid addressing with each subnet mask. Something like https://dnsmadeeasy.com/support/subnet/

[Daemotrix]

Okay I try to use .2.0 network thanks a lot.