@KidaT If you open the BE800 US support portlal - https://www.tp-link.com/us/support/download/archer-be800/v1/#Firmware You won't see this FW release because it's a brand new - I assume you received...

@Yamshanks Upon successful restart your router should forget any customized password. The default router password is admin. Did you buy this router or it has been provided to you by an ISP ?

@KidaT That's just a suggestion because your FW version is not listed yet on the BE800 support portal. Which FW region your router is - you can check that on its bottom sticker.

@KidaT The error you're getting is most probably because you're not allowed to downgrade to a previous FW release from the curren one.

@Sumitra Here's a general video guide on how to install your router.

@Hokr_1970 So basically you're telling that the RE works only when is near the router, but when you place RE where it should be the connection brakes ? Is that correct ? If that's the case check this...