Is your husband's laptop available to connect to 5Ghz? Will this lag your out your PS4. It seems to be some compatible issue, you may email or phone TP-link support for help.

You may also check the TP-Link products: http://uk.tp-link.com/products/details/cat-9_Archer-C5400.html This model also support MU-MIMO. For your questions, 1. The speed of different devices may be...

I think you can call the tech support hotline to let them guide you throught

Sounds complicated. You may send email to tech support of tp-link to see whether they can help.

As I know, the devices would re-connect automatically as long as the wifi name and password haven't been changed. But when you upgrade the firmware for the router, it will take several minutes, while...

You may try to upgrade the firmware first according to this link: http://www.tp-link.com/en/faq-1562.html There is a new firmware for the disconnection issue on Smart bulb and HS105.