QUOTE(thankyou @ Mar 2 2013, 01:16 AM)
Don't think they authenticate based on MAC address because I had my HG8240 successfully configured to replace HG850a.
Try to open up the saved configuration with notepad/browser and look for the field as below:
<PassWord PassWord="0000123456"/>
PassWord is the optical authentication between Huawei ONU & OLT (not too sure about other brand though).
What you can do is, reset the new HG850a to factory settings, and insert the PassWord through web interface by using "telecomadmin" username then save and reboot the ONU.
If you stay in PJ area, I wouldn't mind lending you the HG8240 for you to test it out...
Thanks. Let me try it later or tomorrow. I actually backup (original BTU) the configuration file and restore it to the used unit (2nd BTU). Should be the same configuration ( I think but not sure ). Like my TPLINK router, if I do that all the settings will be exactly the same. With the in my mind, the 2nd unit = 1st Unit but still the 2nd unit link still not able to get connected. The link light keeps blinking.
Anyway, let me test it out and if I am leave with no choice then I will contact you to borrow your unit (HG8240).
BTW, did you ever bring your HG850a to another friend place with unifi and plug in? I am about to test it with my unit at friend place but not sure if it will change anything to the unit.
Thanks Mate