Hi Jeffatennis,
Do you use the mBlock 3.4.5? Here are two documents for mBot Bluetooth connection with PC to you for reference.2. How to use Bluetooth module with mBot to do wireless program on mBlock.docx.zip (12.3 KB)
27.Why the Bluetooth of my mBot can’t connect to my computer.docx.zip (71.5 KB)
If it still can’t connect to the PC but works with mobile device, maybe the Bluetooth adapter on PC dosn’t suitable for the Bluetooth module. In this case, the 2.4G wireless serial should be better since it has included the 2.4G usb dongle for PC side and it is plug and play.