It would be in the number of DHCP addresses allowed. If it's limited to only 3, then a 4th won't be assigned an IP address.
Are you able to use a browser on that computer and just can't see shared folders?
I wonder if anyone has yet found an answer to the missing computer on the network list problem?
I have four on a network as follows -
Laptop Windows 10 64 bit - Listed on 'network'
Old laptop Windows 10 32 bit - Listed on Network
PC windows 10 32 bit - MISSING on network
PC Windows 7 32 bit - Listed on network.
I have tried most suggestions to be found on various forums, but no success so far. Any help would be appreciated.