The answer to my question is as follwoing:
I ordered a SG300-52.
To assign a static IP on a DHCP client which is connected to a specific PORT, a DHCP server is needed for every PORT.
For example:
PORT 1: 192.168.178.1
PORT 2: 192.168.178.2
PORT 3: 192.168.178.3
...and so on.
I tryed the following:
- set the switch to L3 mode
- created a new VLAN
- added the PORT to the VLAN
- set up a DHCP server for that VLAN/PORT
But the problem is:
- a DHCP server for the PORT requires a IP RANGE with more that one IP, so that it is not possible to add a single IP to a singel PORT
- on the other side the DHCP server defined a not changeable default gateway on the DHCP client (but in my case I need a special default on each DHCP client)
Therefore, a switch is no option to configure my network.
Case closed.