Throughput
Speed
Distance
Received signal strength indication (RSSI) signal strength
Effective isotropic radiated power (EIRP)/power settings
Antennas - Placement, Type and Polarization
Channel utilization
AP association time - How long it takes a client to associate with the wireless router or access point.
Site survey - Identifies the number of access points and their placement to ensure a building or area has sufficient wireless signal coverage.
Interference - Caused by other devices which emit radio frequencies on the same wireless band as the wireless network. In channel overlap, the wireless routers and Access Point (AP) that operate on overlapping wireless channels.
Antenna cable attenuation/signal loss - As a client goes further away from the wireless router or access point, the signal will be weaker.
RF attenuation/signal loss
Wrong SSID - If a client has a stored wireless network within its setting, the SSID of the network is saved as well. If the SSID on the Access Point does not match the SSID on the saved network, the client will not connect.
Incorrect passphrase - If the passphrase is incorrect either on the client or the Access Point, the client will not connect to the wireless router or access point.
Encryption protocol mismatch - If the encryption protocol does not match, the client may not connect to the access point.
Insufficient wireless coverage - If a client is within a vicinity of poor wireless signal coverage, the operating system of the client may not connect due to the poor coverage.
Captive portal issues - If the captive portal is misconfigured, the client may not be able to access to resources on the network.
Client disassociation issues - The client may disconnect from the access point due to signal loss, cyber-attack, changes on the wireless network, etc.