Connection timeout - Why?

Hello everyone,

I'm having trouble connecting to the wifi network in my new apartment. It's a shared flat and my roommate connects without any issue. I have no problem connecting with my phone, but with my MacBook Air, it’s impossible to connect; the message "connection timed out" keeps appearing. I tried turning the router on and off, but to no avail. The problem seems to be with my computer since my phone works fine... I haven’t updated the system in a long time due to lack of space, but is it time to do a big cleanup to install the updates?

Thank you so much in advance for your help; I'm not very knowledgeable about computers, but I'm determined to improve and solve my issue!