If you are using PMP 450d, Please read this.
In the software (Release 14.1.1 or earlier), the PMP 450d had an incorrect gain setting applied which results in limiting the radio tx power in order to stay within EIRP limits. This is especially impactful in the 5.4 FCC band. This leads to 9dBi less gain than capable, which leads to link budget loss of 18dBi. The 450d has an overall gain of 25dBi which is comprised of an internal 9dBi patch and a dish that adds 16dBi to total 25dBi of gain. The radios were incorrectly configured with 25dBi of dish gain which leads to incorrect EIRP limitation calculations.
In order to fix this, you can simply upgrade the 450d radios to the latest 14.1.2 Open Beta build, which can be found here. That will automatically adjust the gain permanently. You can then downgrade the 450d device to your current load and the gain will remain correct.