I recently ordered myself an Archer C7 to play around with, for the price it seemed like quite a decent unit, offering dual band 2.4GHz and 5GHz, guest network and gigabit LAN ports.
Since I have some older devices I configured both the 2.4GHz band and the 5GHz band.
After this I noticed on my Macbook Air if I connected it to the 5GHz network, traffic was hit and miss. Sometimes I would have LAN access, others I did not, and the same went for internet access. However, if I connected to the 2.4GHz network everything operated normally.
I emailed TP-Link support about this and they asked me to perform a variety of tests and although some of my devices are still not working correctly one of the suggestions they made did fix the issue on one device.
If you are having this issue, make sure you run all of the EFI and SMC updates for your Mac, after I installed these I was able to connect to 5GHz with AES using my Macbook Air
Note: This particular issue from what I have read seems to be isolated to wireless cards that use the Broadcom Chipset (which unfortunately is a lot of Apple products)
TP-Link apparently have senior engineers working to fix this issue (as it has been noted that there are throughput issues with broadcom cards as well), however in the meantime if you want to use the 5GHz band it is recommended that you leave the network with open security (i.e. No passwords) and set up MAC address filtering to prevent unauthorised access. This is definitely not a “fix” more of a band-aid solution, because seriously what home user is going to add a MAC address every time they want to connect a new device.
If you still seem to have issues connecting after doing an SMC and EFI update it is recommended that you make your Mac forget the networks – make a new network location and then try to connect again. See this document http://support.apple.com/kb/HT5289 for information on network locations.