Hi @Rl8x 

In fact, the range is based on the real environment. The distance stated in the device specification is tested in a very ideal and open environment. In a real environment, there is a lot of interference that will limit the range. Also, as the communication is bidirectional, the distance also depends on the device's ability to receive the signal.

"Based on field tests. The real transmission range may vary, according to the environment, receiving device, etc." The statement has already been mentioned on our promotions page.

 You can try adjusting the channel and channel width to see if the Wi-Fi signal can go further, and you can also try different devices for testing. Adjusting the transmission power is also a good choice.

  @Rl8x 

For more information, please refer to the following link: https://www.tp-link.com/en/support/faq/2511/.

To find a less crowded channel, it is recommended to download a Wi-Fi analyzer tool. 

Have you used the original power adapter to power the device? Additionally, you may want to try replacing the Ethernet cable.

Also, please take a look at this link:https://community.tp-link.com/en/business/kb/detail/298

  @Rl8x 

You installed the two white dipole antennas, and positioned them at a compound 45' angle?

Did you ever power up the unit without those antennas being connected?

  @Rl8x 

Sounds like your unit is defective then, not that I'm saying 300m for 5.8Ghz is remotely real, but you should still see 100Mbps grade signal at 30m.

The antenna position improves longer range communications by offering different spatial diversity options, but it's like the 'last 5%' not the first 90%.

  @Rl8x 

That device should absolutely do 50Mbps at 30m...possibly even at 2.4G depending on the local RF environment.

Are you able to measure the signal strength (RSSI) from the device using an app on a phone or similar?  At about 1m, you should be seeing a strong signal in the range of -30 to -50 dBm.  At 20m that will likely drop into the -70 to -80 dBm range.  As long as you are above -90dBm at your desired use point, you should have >10Mbps of performance.

By the last 5%, I mean that most of the work is done by the radio+antenna.  By tilting the antennae into a V (technically more a canted L ) you create a 90' phase alignment between the antennae which means one sends a signal oriented on 0' and the other 90', commonly referred to as H(orizontal) and V(ertical) polarization.  Signals/waves that are 90' out of phase with each other effectively don't 'see' each other during transit.  So, in complicated RF environments (noisy, obstructions, distance), having the ability to send the signal at least 2 different ways is often helpful, likewise on the reception end.  Even if there is a mismatch, ie station A is a V and station B is just an I, you can still leverage either polarization, you just lose some (the 5%**) gain/power due to the antenna mismatch.  **Not even remotely close to an actual number.