I have issue on AP Metal 52ac (RBMetalG-52SHPacn, chip Atheros AR9888, CPU MIPS 74Kc V5.0, firmware 6.45.9) working in ap bridge mode on 2Ghz-B band with clients handhelds Symbol/Motorola mc9060, mc3190, mc9190.
Clients have large percentage of missed beacons at times - 45% with 1-3 clients per AP and up 65% with 20-30 clients per AP, that leading to frequent roam and packet loss.
Signal level on clients -40..-65 dBm.
In the same time with Metal 2SHPn, Atheros AR92xx, MIPS 24Kc V7.4 all works fine - maximum percentage of missed beacons - 5% with 30 clients.
RouterOS v6.46.8 on both models of APs, settings of the wireless interface are the same in both cases.