I only see an entry on this subject from several years ago. Whenever I mirror (through Apple TV) with my tv my MacBook Pro disconnects wifi. It is not one network, it just does not allow for any wifi use. I had no trouble with my old MacBook or with my phone.
Certain displays can emit harmonic interference, especially in the 2.4GHz band between channels 11 and 14. This interference might be stronger if you're using a notebook computer with the lid closed and have an external monitor connected. Try changing your access point to use 5 GHz or a lower 2.4 GHz channel.