It's important to check the version of the Bluetooth standard that all your individual Bluetooth devices support as well as the adapter that receives the signals. If both the adapter and devices support the latest 4.0 / 4.1 standard they will benefit from greater efficiency and performance and likely suffer less from interference.
The best way to find out the version of Bluetooth supported by your individual device/s is to examine them for their exact model number. With this information then search on-line, ideally at the manufacturer website for the device. Manufacturer documentation should clearly state what versions of Bluetooth are supported. If you can’t find the answer in documentation an email or call to them or the company that sold you the device should clear things up.
If you can't find the manufacturers website or they don't disclose this information it's possible that you can find out by searching for the devices product information page on a large on-line retailer.
Having checked your devices, if you discover that any particular device in your Bluetooth setup is using a very out of date version of the Bluetooth standard it may be time to consider an upgrade of that component. Remember, if your using devices that send a lot of data such as constant streaming audio or video then you really want ensure that both adapter and device are at least compatible with Bluetooth version 3.0 + HS.
One other thing to check; if you have multiple Bluetooth devices does a specific one have a problem and also have much older Bluetooth support than the rest of your setup? If so it may suggest that this device needs an upgrade to a similar device compatible with the latest Bluetooth standards.
I need help finding a replacement Bluetooth compatible device
If you were not able to determine the Bluetooth revision supported for any of your devices click here for some other ideas.