my computer doesn't see the router

please do the following:

1. unplug the modem from power for 2-3 minutes. Then power on.
2. unplug router from power for2-3 minutes and reposed.
3. restart iMac in Safe Mode then restart normally and test. Safe mode can take up to 10 minutes!

Hello cherzart,

Thank you for reaching out in Apple Support Communities. If we're understanding correctly, your Mac is unable to detect a Wi-Fi network. We can help point you in the right direction.

To help troubleshoot this behavior, we recommend to follow the steps outlined in this helpful article: If you can’t connect to a Wi-Fi network on Mac

There's also additional steps outlined here, that may help: Solve internet connection problems on Mac

Please keep us posted with the results.

Best regards.

Instructions are in Use Safe Mode to isolate issues with your Mac

Please use How to get old versions of macOS to get Catalina.