my Macbookpro won't connect to my wifi; wifi is working fine for my iPhone and other computers

sometimes the 'could not be joined" is because at some point the password became corrupted. If you think this might be the same, write down the correct password on paper, then select and Delete [-] the troubled network-name in this pane:

when next you select that network, it will establish a NEW connection, and demand the NEW password (from the paper).

what model-year MacBook Pro?

hold down the Option key and click the Wi-Fi Icon in the menubar, you get a snapshot if current parameters. Screenshot, photograph, or transcribe those values. look like this older version:

...

signal strength (RSSI) is an excellent -45, where around -40 is right next to the Router, and -70 is unusable attenuated.

Noise is very good at -95 dB.

you have connected in the interference prone and typically very busy 2.4 GHz band, which for many users in densely populated areas is completely overwhelmed and unusable.

you make a 20 MHz channel connection on channel 6, and are getting the absolute best speed possible using both of your Mac's two antennas and 64 patterns per signaling interval to attain the top speed there, 144 M bits/sec.

¿what was the issue again?

the best way to configure your extenders is as 'dumb' access points with the same Network-name. Then they merely allow connection, but do Not provide DHCP addresses. Apple calls this "bridge mode", some other refer to this as 'extend an existing network' but every vendor seem to call it something different.

when you do that, the extender(s) allow connection, passes your DHCP IP Address request to the MAIN router, which issues a local DHCP IP Address, and you are on and connected.

system preferences > Network > Wi-Fi > (advanced) ...

first pane should be labeled Wi-Fi

it may have moved a little but not too far. Still in the same place in Ventura.