Why not try to delete the profile and reconnect to the extender with the password? Does it work? what is the hardware and firmware version of the extender? You may able to update its firmware. and...

To build a VPN connection, the IP address of 2 LANs should be public IP address. and what is the hardware of the MR6400 and what is the current network topology?

who is your ISP? what is the speed you can get from it? you can connect your computer to the C8 by wired cable and wifi separately to run the speed test and post the results. While do not forget to...

to cover the whole house and get the gigabit speed, you may consider deco series products, like Deco M5. deco M9 plus. https://www.tp-link.com/en/search/?q=deco&t=&s= they can build a whole house...

here are some smart bulbs which support multicolor, including KL130, LB130, LB230 https://www.tp-link.com/en/products/list-5609.html there is a power strip called HS300 available now:...

considering the budget and your request, there are some products may satsify your needs, including archer C7 Archer A7 and Archer C9.