We have a CAPsMAN installation with about 50 RB951G-2HnD as APs. Last month we decided to replace most of the APs by newer models with 802.11ac support, e.g. hAP ac lite and hAP ac. The APs are powered over passive PoE with MikroTik RBGPOE. After configuring and installing the APs everything looked fine. Unfortunately we realized that on some of the 20 hAP ac-s the 2.4 GHz radio doesn’t work correctly. We did some troubleshooting and testing - at the end we think that it is a power problem of the hAP ac devices when they are powered over PoE on longer (>25m) cables. The following effects occur:
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- When a hAP ac is powered directly with the included 24V 1.2A power adapter they behave as expected and the voltage from Sytem:Health is 24.1V.
- When a hAP ac is booted over PoE (with the RBGPOE and the 24V 1.2A power adapter over a 30m UTP cable) voltage drops to 23.5V. The 2.4 GHz radio behaves very strange (the configured SSID is sent but either it’s impossible to connect or the effective data rate is very slow at about 1-2 Mbps). Connecting a separate 24V 1.2A power adapter after the boot-time doesn’t help.
- When a hAP ac is booted by a directly connected 24V 1.2A power adapter and afterwards the ethernet cable (with PoE) is plugged into port 1 and the directly connected power-plug is removed the hAP ac still works perfectly.
- The 5 GHz radios aren’t affected.
- Both software versions 6.34.4 and 6.35rc49 show the same effects.
- The hAP ac-s lite aren’t affected - everything works fine on them.
We tested these procedures several times with different hAP ac-s and ask ourselves whether we should buy more powerful 48POWs or wait for a firmware update that fixes this issue.