[Moose Test]

Suspect either a CEM failure, or a wiring and/or module fault which is disrupting CAN bus communications.

For that number of modules to all claim communications errors, it either has to be a "network" fault, or the module common to all in terms of function (i.e. the CEM) to have failed itself.

Personally, I think good next steps would be:
a) Check the CEM and its connectors for corrosion

b) Find a copy of the wiring diagram online (helps with understanding module location on the vehicle and how they are connected) and check all the connectors and wiring for obvious physical damage

c) If all else fails, get the error codes read by the Volvo VIDA/DICE tool which will be far more specific about which modules those codes come from, and which can show the overall health of the network.