How about searching on Google? I found a lot of answers on internet.

How about contacting TP-Link support by yourself? Normally if there is a new update, it will be published on the website.

Your problem is not caused by the mac address. Pay attention to the distance when the wireless drops. It is normal to drop from wireless when the signal is weak.

The proxy mode can't be turned off. I found almost all the range extenders have the same issue. However, if there is no mac filtering or other advanced features on the router, proxy mode won't affect...

Any way it is ok now. ;)

The cat5 cable only supports 100Mbps. You need a cat5e cable, cat6 cable better.