I finally solved this using the WOL broadcast plugin. Steps:
- Created WOL broadcast with the public ip of the site where those computers are
- On the router from the second site added static arp for private ip 10.148.17.254 to mac ff:ff:ff:ff:ff:ff (broadcast)
- On the same router forwarded port 9 udp to 10.148.17.254
You can mark this as solved. Thank you!
For others: The remote site has computers with activated and working wake on lan and the router configured for DHCP with next server the IP of the FOG server and filename undionly.kpxe (for legacy BIOS boot).