clarklc1 wrote

However, I cannot access the AP; I repeatedly receive a message that the password is incorrect.

iPhone7 is known to have WiFi connection problems. See Apple's recommendations to fix this, especially step 7: https://support.apple.com/en-us/HT204051

Also make sure the CPE settings are correct and there is enough distance between the iPhone and the CPE. If the distance is too short, the powerful radio of the CPE can overdrive the WiFi receiver of the iPhone. Ensure the iPhone is in the area of coverage (antenna beamwidth of CPE510 is 45°), this is much more critical with 5GHz CPEs than with 2.4GHz CPEs.

As for your garage: The CPE performs best on directional long-range links. If your garage is far away from your house (hundreds of meters or more) a directional link makes sense. If it's near to your house, an EAP110-Outdoor would be a much better choice, especially if you plan to connect wireless SOHO devices rather than wired devices to the AP in the garage.

winstar wrote

Thanks R1D2 for your detailed explanation,while I am wondering what on earth would happen if the power of the CPE is rather high? Will it damage the Wi-Fi receiver of iPhone? Or just cause a bad performance?Since I never heard about the higher signal strength will cause such problems except from higher interference.

No, a high signal level does not damage the WiFi receiver, but it will overdrive it causing all sorts of interferences. That's the reason why professionals always decrease the TX power of an AP to a level suitable for the actual area to cover rather than increasing it to the possible maximum, especially if there are lot of APs nearby. Some APs do this even automatically with a technique called antenna beamforming.