Bluetooth compatibility/functionality is not universal as there are many combinations of hardware, software, Bluetooth drivers/profiles, etc and all need to match up correctly to have full functionality. As long as the device that the Sennheiser Bluetooth headset is being connected to supports the appropriate Bluetooth version (usually 2.1 and EDR for Sennheiser products) or higher and the appropriate Bluetooth profiles (A2DP, HSP, HFP, AVRCP) there should be no connectivity issues. When connecting a Bluetooth headset to a standard device (like a cell phone) for a standard application (like music listening or voice calls) the device will typically utilize a relatively standard Bluetooth protocol and hence a headset will usually be compatible without any issues.
NOTE: On some devices (like cell phones) the settings of the device need to be adjusted to accommodate Bluetooth devices. For example many Bluetooth headphones incorporate a microphone and hence the device's (ie: cell phone) settings must be set up accordingly. In a situation when a Bluetooth headset also has an integrated microphone then the device's settings often need to be set to a "Hands Free Profile" (HFP) to allow the Bluetooth headset to interact correctly with the device. NOTE: Sometimes an update will have occurred on the device that the headphones are being connected to and it requires the device to be rebooted (ie: turned completely off and then back on) before the headphones will connect.
As outlined above there are many factors that affect Bluetooth connectivity and compatibility (including the Bluetooth version, Bluetooth profiles and protocols in use, etc) however there are many other factors that will have an influence on connectivity and functionality of a Bluetooth headset and these include things like power and quality of the Bluetooth transmitter in the device you are connecting to, the distance between Bluetooth devices, the environment that the devices are being used in, the amount of Bluetooth signals in the environment, etc.
To resolve any compatibility, connectivity or functionality issues it needs to be determined where the issue is originating so that the underlying issue can be addressed. You can test many of these factors with a process of elimination by changing one aspect at a time.
For example if you are having intermittent Bluetooth connectivity on one device (ie: computer) a good test is to connect the headphones to a different Bluetooth device (ie: cell phone). If the connectivity issues only occur on one device (ie: the computer) and not the other device (ie: the cell phone) then that would indicate that the headphones are fine and the issue is actually with the computer.
For example if you are having intermittent Bluetooth connectivity on one device as you move around then it could be a range or wireless environment issue. To test the range start by keeping the two Bluetooth devices close together. If you have good Bluetooth connectivity at close range and only start having connectivity issues as you extend the range (ie: distance between the devices) then that would then indicate that in the environment you are in range is a factor and hence you must keep the devices closer together. Please be aware that at best the range of Bluetooth is 10 meters (about 30 feet).
NOTE: A common cause of Bluetooth connectivity issues is a corrupted Bluetooth connection between the Bluetooth headset and other Bluetooth device (ie: cell phone) so it is often best practice to delete the connection between the Bluetooth headset and other Bluetooth device (ie: cell phone) then turn off BOTH the Bluetooth headset and other Bluetooth device (ie: cell phone). After BOTH the Bluetooth devices have been turned off completely let them sit turned off for a minute or two and then turn BOTH devices back on and re-establish the Bluetooth connection between the devices.
NOTE: If prompted for a password/PIN during the connection process the default number is "0000".