@p4cm4n OK now that you have the password parts worked out, you should be able to go into FOG Settings->FOG Kernel and from there you can downgrade to the 4.15.2 kernels, just download both bzImage and bzImage32 for the PC platform. From there it will download the kernels. You can check by going on the FOG server console to
cd /var/www/html/fog/service/ipxe
file bzImage
That should print out version 4.15.2. If that is the case you are golden. FWIW, you CAN do this while you are imaging as long as you don’t currently have a system pxe booting.