The system is currently working fine, all that I can't do is get all the PC's to see one pc that is in a different part of the house..Internet access is quick, download speeds are as good as the provider (by their own admission) can manage, the PC's attached to router 2 all see each other fine and data loss is not a problem.

As such why do I 'need to set the network up properly''?

Can (some) people please give advice rather than facetious, patronising, comments.

Thanks.

Just a thought, but assuming you now have only one DHCP server having converted the other routers to switches, are all the pc's now on the same subnet? If any IP addresses are on a different subnet, then they won't be seen. Make sure that those that can't be seen are not using static IP. Then use ipconfig /release and then ipconfig /renew from a command prompt to force them to update correctly.
As far as "throughput is faster with a modern software based switch in a router", that sounds like a load of spherical objects and has no basis in fact.

Edited by deleted (Fri 11-Dec-15 22:35:59)

Is this one PC connected by wireless because it may be you have wireless isolation turned on?

Edited by deleted (Fri 11-Dec-15 22:47:11)

Just a thought -
how do you quantify 'can see each other'?
I've had the situation where machines don't show in the display for 'network', but can be accessed by IP address (first level test is to use ping) in the file browser window

I've always used full UNC's (IP addresses can change) to correct problems in the past i.e. \\ComputerName\foldername\filename. I've also found in the past that checking that file and printer sharing was enabled sometimes resolved addressing errors.