@Faurel There are several things here.
The no valid offer received, indicates it either did not receive a dhcp packet without the next server and boot file listed or what it was given didn’t satisfy the request.
Let start with something that jumped out at me first. The pxe booting computer is being issued an 192.168.10.72 IP address (this is good so we know its receiving a reply). And your FOG server is on 192.168.3.93. That tells me they are on different subnets or you have a pretty wide network mask. Are these two devices on the same subnet?
If they are on different subnets, what is the dhcp server the workstation subnet? Is it possible you don’t have the pxe booting values set in the scope for the workstations? Or there is another dhcp server in play here?
Also make sure you don’t have white spaces around your dhcp option values I’ve seen a trailing white space on a parameter mess up dhcp too.
Lastly what device manufacturer and model is your dhcp server? Some SoHo routers will point dhcp option 66 to them even if there is a valid dhcp option 66 activated, but I don’t think that is the case here because the client is complaining about not getting any valid offers. Also on your dhcp sever make sure it issues both bootp (older) and dhcp (current) pxe booting values. These are kept in two different places in the dhcp server’s response packet.