1. Ensure you connect the 5GHz SSID and test. 70Mbps is probably 2.4GHz.

2. WPA-PSK

3. Other settings default.

I am 100% sure that I connected to the 5GHz network (the 2.4GHz gives me similar numbers). The Security is ste to WPA-PSK and I tried default settings, I tried changing the channels, the channel width, turned off any uneccessary feature. I'm starting to think I got a bad unit.

Here's a new development: it seems that only the speed from the client to the server is affected, while the other way around, I can easilty get close to 300 Mbps.

If you are getting different speeds depending on which direction you are sending data, that almost always is an issue with ethernet link speed negotiation (or lack thereof).  For example if you set the EAP245 to 100Mbps on its wired connection, and the switch port to 10Mbps, you would see that type of issue.  You can also see that where one side of the connection is set to autonegotiate, and the other is fixed.  That can cause the autonegotiating device to just guess at a speed and duplex, usually incorrectly.  These days, you almost always want to leave devices set to autonegotiate speed and duplex, and with rare exception it works properly.

Yes, I thought about this as well and I made sure that the settings were set correctly, but the problem still persisted. I did run the iperf3 test for a couple of hours and I did notice that from time to time, for about 30 seconds to a minute, I could see close to 400 Mbps and then back to the usual 50-60 Mbps. I did return the device yesterday and I now wait for a new unit and hopefully, everything will be fine.

I got the new unit today and the problem still persist, so I'm starting to think that there may be a problem on my end (or the entire series is completely broken).

The switch that I use shows that the ports are set on Auto (1Gbps fdx), the cables support Gigabit speeds, I let the controller on its default settings, except for dividing the single SSID into two networks. Am I the only one that experiences this?

The problem has been solved (it was a port issue after all) and the new EAP245 is working great.