@Sebastian-Roth

$ip a s
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 08:00:27:68:16:78 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.2/24 brd 192.168.1.255 scope global noprefixroute dynamic enp0s3
       valid_lft 5677sec preferred_lft 5677sec
    inet6 fe80::971a:3ed0:398c:508c/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 08:00:27:21:31:27 brd ff:ff:ff:ff:ff:ff
    inet 192.168.56.101/24 brd 192.168.56.255 scope global noprefixroute dynamic enp0s8
       valid_lft 990sec preferred_lft 990sec
    inet6 fe80::696d:9af6:dacf:126c/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
4: enp0s9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 08:00:27:e0:79:5a brd ff:ff:ff:ff:ff:ff
    inet 172.30.0.1/24 brd 172.30.0.255 scope global noprefixroute enp0s9
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:fee0:795a/64 scope link 
       valid_lft forever preferred_lft forever

172.30.0.1 - here FOG is DHCP server
192.168.1.2 - there is another DHCP server.

when a client is booting from 172.30.0.0 - ok
when a client is booting from 192.168.1.0 - it can connect and download from TFTP. Then to continue booting client is receiving http://172.30.0.1/.../boot.php
I changed 172.130.0.1 in file default.ipxe to the hostname of FOG.

After this clients from both networks can start fog menu, but from 192.168.1.0 without background image.

The next problem is that I can not deploy the image in the 192.168.1.0 network as by pressing the button Deploy image (on the client side from fog menu), client again receive hardcoded IP address 172.30.0.1

Networks are not connected.

@Sebastian-Roth

But what you actually should look into is setting up a storage node in your other network, hmmm?!
Yes, it sounds like the best way. Could you give me some link with instructions for setup and configure network node?

@Wayne-Workman No it doesn`t work. Even if DHCPd is stoped client is receiving IP address of FOG from the second network via iPXE

Networks are not physically connected.

On first network FOG act as DHCP
Second network has it own DHCP server.

Everything work good on first network

On second network dhcp options next-server and 67 are configured? so client connect and download from tftp normally, but from ipxe client is receiving address of first network.

I tried to edit file default.ipxe and changed hardcoded ip address to dns name. After this clients from both networks can start fog menu, but from second without background image.

The next problem is that I can not deploy the image in the second network as by pressing the button Deploy image (on client side from fog menu), client again receive hardcoced IP address of first network.

Total I have a fully working server on the 1st network and not working in the second network.
How to configure FOG to work in 2 networks?