2010 S80 losing acceleration

[Loni]

My 2010 S80 has begun to lose acceleration intermittently. When it loses acceleration, the RPM’s go up, but the car will not speed up and makes a whining sound. If I turn the car off and back on, it accelerates again normally, and the fan also starts to run loudly. This was happening every few weeks, now it’s a few times per day. Any ideas or advice?

 

[Shaggy]

the RPM's go up, but the car will not speed up and makes a whining sound

That's the transmission slipping, and it's getting worse. Restarting clears it for a while, which points at the transmission going into a fault mode. I'd get the transmission codes read (a generic scanner won't always see them) and check the fluid condition before it gets worse. How many miles are on it?