Do the cable test and see whether if it is the problem from the ethernet cable? Make sure that your connection between PCs and switch is normal. Or change another cable to check. If it still doesn't...

It is too complicate and you also don't mention the PVID of each port. I would suggest that you could send email to [EMAIL="support@tp-link.com"]support@tp-link.com[/EMAIL] for help.

Maybe you are using EU firmware which need to obey the CE Certification, so CE only allow 5Ghz Band 1 channel (36.40.44.48). Also the transmission power obey the law.

I think your EAP320 is broken. You could try to use reset button and access the web UI of EAP320, if you cannot access the web UI, you may need to return the product.

Refer http://www.tp-link.com/en/faq-865.html and find answer in Q11.

You cannot change these device names for each EAP, but you could divide each EAP and name them in EAP controller.