Q: wifi issues 10.9.5

Try running Wireless Diagnostics.

Troubleshooting Wi-Fi connection issues - MacBook Air (Mid 2013)

Troubleshooting Wi-Fi issues in OS X

Wireless Connection Problems - Fix

Wireless Connection Problems - Fix (2)

Wireless Connection Problems - Fix (3)

Wireless Connection Problems - Fix (4)

Wireless Diagnostics - About

Also try turning off Bluetooth

it seems there is a systematic problem where 10.9.5 is incompatible with some (older?) kinds of routers. yeah, an update that makes our computers less functional - thanks, apple. see this thread and try what it says: https://discussions.apple.com/thread/6548804

else, may have to go back to an earlier version of the OS

Apple doesn’t routinely monitor the discussions. These are mostly user to user discussions.

Send Apple feedback. They won't answer, but at least will know there is a problem. If enough people send feedback, it may get the problem solved sooner.

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