Default [Q] MAC address change after flash

Hi all,
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To my work, I can access to the WIFI by giving my MAC address. I gave my MAC address, and ok, I had access.
However, I flashed the rom CloudyG3 and following this, no access to WIFI... I've realized that my MAC address had changed (and I saw I 'wasn't alone in this case) ... So I did a new request for an access with the new MAC address, and it doesn't work ...
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I used the application Wireless mac address change to replace the current MAC address with my old address and I regain access to the corporate network ...
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So is there anyone could help me to find my old MAC address? I tried to reflash my phone, it does not change ... I tried to pass on the Rom OptimusG3, the MAC address remains on the new ...
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Thank you in advance for your help