tcsmaxx wrote

The three access points EAP110 have in my opinion insufficient tx power, at a distance of 5 meters mobile phones have only 3/4 reception bars. And after about 50 meters, the connection breaks off.

At what height did you mount the EAP110-Outdoor?

Note that cell phones often have weak antennas and therefore their WiFi coverage is very limited (max. 50m for 802.11b/g is no big surprise). What's more, signal power is not the important parameter for good coverage (and it's limited by regulatory provisions). Much more critical is signal-to-noise ratio (SNR). To determine wether you have a good SNR at your place, use a heat-mapper running on a laptop with better antennas compared to those of mobile phones. If SNR can be improved, signal quality and coverage will increase for all devices.

To improve SNR, you could try to set 802.11n only mode, 20 MHz channel width and fixed, non-overlapping channels for the EAP110-Outdoor (1-5-9-13 if using 802.11n, 1-6-11 if using 802.11b/g/n mixed mode). In most cases, this gives better results than just increasing TX power, which often increases interference and thus makes SNR even worser.