Volvo D13 Actuator

Hello all,
2013 Volvo D13
Occasionally I lose boost. This is VERY arbitrary!! Arbitrary? May happen once then will not happen for a month or so. It may happen for less than a minute then normalizes.
Brought to mechanic, hooked to computer. Computer shows a problem but no description. Mechanic saying actuator should be replaced but not sure about turbo until replace actuator. This generates a few questions:
Loosing boost arbitrarily-
Would this indicate the actuator going bad? (Does an actuator gradually fail or is it "all or nothing"?)
Could it be electrical vs mechanical?
Could turbo be going bad?

Thanks in advance,
Tee