There are sometimes after PE Boot, and you need the right drivers for nic or whatever.
This is how you inject the required drivers to a boot.wim

DISM TO MOUNT AN IMAGE:
Dism /mount-wim /wimfile:C:\new\Win10Boot.wim /index:2 /mountdir:C:\tmp

INJECT DRIVER
dism /image:"C:\tmp" /add-driver /driver:"C:\drv\folder" /Recurse

COMMIT AND DISMOUNT
Dism /unmount-wim /mountdir:C:\tmp /commit

Useful Commands
Dism /Image:C:\tmp /get-drivers
Dism /get-wiminfo /wimfile:C:\new\Win10Boot.wim

* Make sure you inject drivers to the right index.