Formula to extract text between constant strings

I have a field that contains two strings that will always be constant: " - Device S/N: " and " - Dongle key S/N: ". I want to extract the serial number from in between these two constants. My biggest issue is that the character positions will always vary.

Any ideas on how I can do this? MID, LEFT, MATCH, don’t seem to work at all.

Here is a sample of the cell contents that I am working with:

Device name: NewTom GO 3D - Device S/N: 708K0078 - Dongle key S/N: 1-1555622170