The OP said the following in his last post, "I don't have a router, never had one running. This problem recently started, before a week. Maybe just reinstalling dhcp will be a good idea."
If he has no router and he's still getting the wrong DNS address then he should only have to go into his DHCP server settings and correct the DNS address (ie: make it 192.168.1.1) so that clients get the correct info.
However, I suspect he actually does have a router running DHCP in the mix somewhere because he has stated previously he has some client PC's with 0.x and some with 1.x
Regarding the above, check your DHCP server's settings and correct the DNS IP if that is the problem. Also, you said above, "Dhcp is scoped from 192.168.0.1 - 192.168.0.255. " Adjust the scope to 192.168.0.100 to 192.168.0.199 as you always want to leave some IP's outside of the DHCP scope to be used for static assignments such as servers and network printers.
Also, detail your exact setup for me. These days (for most folks) it looks as follows:
internet >> SOHO Router >> clients/servers
If you don't own a SOHO Router, I highly recommend buying one. Once you have it, before plugging it into your network you will want to disable DHCP on your server. Then plug it in and set it up according to the setup guide and your IP addressing problems should all go away.
If you have more clients than can be plugged in to a SOHO Router with 4 LAN port's you'll require a switch and it should be plugged in to a LAN port on the SOHO Router.