直接上解决方案，最近升级到2.5.18的用以前的办法会跳转回去，无法实现频道分离。
国外大神的解决方案：
Before you try to change the SSIDS run the below command on each device. This turns off automatic merging of the two SSID's back in to one SSID after a reboot. (This is the most common issue on the latest firmware).
config set wifison-monitor_stop=1 （这步很重要！！！）
config commit
The commands below will then set the the 2.4Ghz and 5Ghz networks to the names you want:
config set wl_ssid="YOUR SSID 2.4Ghz NAME"
config set wla_ssid="xx_5G"
config commit
Only reboot the RBR50.
只需要重启RBR50即可。
Switch the satellite RBS50 off once you have issued the command and don't bring it back online until the RBR50 has fully rebooted and settled and you can see both SSIDS's. Once the RBR50 is back on line and both SSID's are availabel switch onthe sattelite RBS50 and let it settle. It will also begin advertising the new SSID's。
拔掉RBS50的电源，等RBR50的无线信号出现后再通电。