@Tabsi hello, the reason why it tells you that you need a gateway (router) for that is because fixed address means a dhcp server will assign that address, meaning that dhcp server which is controlled by omada is on omada capable router (er605 or er7206) and those settings are valid only for those routers, it has no effect if you have dhcp server which is not controlled by omada. You can set manually dhcp reservation, under settings->services->dhcp reservation you can add them manually before connecting the device as well as you can add description. However, as long as you do not have er605 or er7206 it means your dhcp server is on some other device which is not controlled by omada, meaning that you have to set on your dhcp server those dhcp reservation.

  @btx Thanks for your fast answer!
I'm using a ER605 and adopted it already with my Omada controller. I also used the DHCP reservation but it still dont work. I restartet the devices where i want a staitc IP but nothing changed.... I have a fibre modem before the r605 is that the problem?

@Tabsi you are welcome, I was just writting my own question when I saw your post, so I replied, did not even notice when you posted.

For me it sounds like if you have done everything correctly, however, if you do not receive ip address, then check:

1. check your lan settings and ensure that you have enabled dhcp server (settings->wired networks->lan), also set correct ip of your omada dhcp server which is optional.

2. if you have any other devices (like your ISP's router) with enabled dhcp, because your devices get the addresses from somewhere and it seems not to be er605.

my first idea would be that you have somewhere additional dhcp server running, make sure you disable/switchoff dhcp on that second device.

@Tabsi I forgot to ask if you renewed your lease, because if your device got first some ip address and you later set fixed ip, you need to either reboot that device or disable then enable it in case it is windows machine.

  @Tabsi I can assure you that dhcp reservation works and if you renewed the lease and your er605 is connected and has the ip address which you defined in LAN as well as enabled dhcp, then the only 3 possibilites left are:

1. there is another dhcp server in same lan

2. ip on that device is static

3. your er605 or oc200 are broken/buggy

Where I must say, point 3 is written only because one cant 100% exclude that option, but I am quite sure you have another dhcp server running.

Why your fritzbox was working, it can be a lot of reasons, for one you maybe did not have 2 dhcp servers running on other side even if you did, you may have enforced that firtzbox is dhcp server, same goes for openwrt where one can enforce specific dhcp when there are several in network.

If your fritzbox is still in your network, make sure that it has dhcp disabled. You also mention that you have another router, well, if that one is in same network, then maybe there you have dhcp server running. Not sure if you have any other devices, just check that dhcp is not enabled on any other device than er605.

  @Tabsi can you draw your topology of how your network is connected?

  @btx  of course, here it is

There are also other devices, but nothing special

  @Tabsi thanks, what I miss on your topology are the subnets/ip's, as I have no clue if they are in any way splitted or isolated, are all your devices from pic in 192.168.0.1/24 range?

So far I do not see anything specific, I am still not sure that you do not have second dhcp, can you check over terminal which dhcp you get and if it is raspberry pi's address? On linux following commands could show you where your dhcp server is (you need to run them as root or with sudo to get a result):

cat /var/lib/dhcp3/dhclient.leases
or 

grep dhcp-server-identifier /var/lib/dhcp3/dhclient.leases

or

grep dhcp-server-identifier /var/lib/dhcp/dhclient.leases
or

#(eth0 is your lan interface, you can check the name with ifconfig command)

dhclient -d -nw eth0
 

Additional notes, check if your rpi has all required ports open, in case you run debian/ubuntu and use ufw, open following ports:

ref.: https://www.tp-link.com/no/support/faq/3265/

sudo ufw allow 29811/tcp

sudo ufw allow 29812/tcp

sudo ufw allow 29813/tcp

sudo ufw allow 29814/tcp

sudo ufw allow 29810/udp