(I'm not an expert with this sort of stuff, so forgive me for any wrong terminology etc.)

For reference, here's what it is, 6th and final generation specifically.

Basically we mainly use it to expand the wifi coverage on the property, since it acts as a wifi hotspot and allows us to create a 2nd network/connection for us all to use and in addition to our original modem/router.

It's been on the fritz lately, was discontinued several years ago, and it doesn't seem like there's anything exactly like it anymore. Any suggestions? Ideally something cheap and easy to set up.