Unfortunately the 2.4 GHz band, which Bluetooth uses, is rather crowded. Therefore interference with WiFi (802.11b/g/n/ax), microwaves, USB 3 devices, etc. are quite common. Apple has a support document on the issue and suggests a list of measures (see the link for all suggestions):
How to reduce wireless interference
These general steps can help achieve a cleaner, stronger wireless signal:
- Bring your Wi-Fi device and Wi-Fi router closer together. Bring the Bluetooth devices that are connecting to each other closer together.
- Avoid using your wireless devices near common sources of interference, such as power cables, microwave ovens, fluorescent lights, wireless video cameras, and cordless phones.
- Reduce the number of active devices that use the same wireless frequency band. Both Bluetooth and Wi-Fi devices use the 2.4 GHz band, but many Wi-Fi devices can use the 5 GHz band instead. If your Wi-Fi router supports both bands, it might help to connect more of your Wi-Fi devices to the 5GHz band. Some dual-band routers manage this for you automatically.
- Configure your Wi-Fi router to use a different Wi-Fi channel, or have it scan for the channel with the least interference. Most routers perform this scan automatically on startup or when reset.
As a first measure, I would strongly suggest to check for the frequency of your WiFi connection. Press alt and click on the WiFi symbol. If under "Channel" it says 2.4 GHz, try switching your router to the 5 GHz band.
To troubleshoot WiFi interference further you can also use the Wireless Diagnostics.app tool. Try Spotlight or head over to /System/Library/CoreServices/Applications. Once you launched the app, you can press e.g. alt+cmd+5 for the performance logger.
Another source of interference are microwaves. I once actually had the issue what when my colleagues would warm their food, my mouse and wifi would stop working. Try re-locating your desk or microwave (or any other source of 2.4 GHz emissions) in that case.
