When the prototype character equips any item, the following is logged in the Output Log:
UActorChannel::ReadContentBlockHeader: Sub-object not in parent actor ...
Although nothing went wrong after repeated testing even with the error logged, I don't know networking well enough either to decipher what the error implies, and what can go wrong. Starting to debug the error is easy however. I use JetBrains Rider and could quickly find the string of error in the engine code, and put a breakpoint there.