You can open the range devices can talk to by adjusting your subnet.
The simplest way set the 3rd octet to zero. But this causes a increase in traffic seen by that device.
Say...
Device 1 has a IP of 192.168.1.1
Device 1 has a Subnet of 255.255.255.0
and
Device 2 has a IP of 192.168.2.1
Device 2 has a Subnet of 255.255.255.0
Devices 1 and 2 cannot talk to each other under those conditions unless you set up routing rules in your switch for it.
Now another method.. Adjust Device 1's Subnet.. 255.255.0.0,
Device 1 can now communicate with Device 2. Device 2 however cannot independently talk to device 1. It can respond to Device 1's requests but it cannot initiate its own. to do that you would zero that third octet on device 2.
This however opens the devices to ALL traffic on the second network. You can do some advanced subnetting trickery by using other numbers, its just a bitmask. Don't zero the 2nd Octet on a 192.168.x.x IP, that gets you into public internet routable address space. If you need class A use the 10.X.X.X IP, that entire block is set aside for private networks. 192.168.X.X is mostly intended for small offices, homes, etc. 10.X.X.X for corporations that would easily exceed the capacity if a class C.
Any private network can use any private IP range regardless of what the thought for it was.
https://www.calculator.net/ip-subne...ip=192.168.1.0&ctype=ipv4&printit=0&x=75&y=21