Yup, that also worked thanks!
For anyone who needs code to expose to blueprints, I made this function.
.h
UFUNCTION(BlueprintCallable, Category = "Online")
static bool GetControllerNetworkID(APlayerController* PlayerController, FString& ID, bool bAppendPort);
.cpp
bool UMyFunctionLibrary::GetControllerNetworkID(APlayerController* PlayerController, FString& ID, bool bAppendPort)
{
if (!PlayerController) return false;
if (!PlayerController->PlayerState) return false;
//ID = PlayerController->PlayerState->GetNetDriver()->LowLevelGetNetworkNumber();
ID = PlayerController->PlayerState->UniqueId->ToString();
if (!bAppendPort)
{
FString null;
ID.Split(FString(":"), &ID, &null, ESearchCase::IgnoreCase, ESearchDir::FromEnd);
}
return true;
}