The default userid and password is most times printed on the device. If not check the user doc. Most times it is admin/admin or such. If you changed and lost the user id/password, then you must do a...

I seen somewhere that 31 is the limit but not sure if it is for each bandwidth. As for VPN, yes it make it more secure but the trade off is a slower connection. On my home network I do not use a VPN...

You could put your game machine on the 5 ghz SSID and your other devices on the 2.4 ghz SSID as 5 ghz is faster.

Can to load the previous version of the firmware for your router that was working? I was able to do it for my Archer C8. It was listed on the TP-Link Archer C8 firmware page. I had to do it so I...

Depends on what you are trying to do. I can see where having two WIFI close together may cause an issue if both are on the same channel. You may want to change the Advance WIFI settings of both WIFIs...

Check to see if your ISP address was changed by your ISP.