Sorry I don't have any other suggestions, you've already gone through the basic things I'd try. It does appear to be an issue with your MXQ Pro box and not your home network, but still not clear if this is a hardware or software issue. Tend to doubt it's hardware as both the WiFi and the NIC chips would have to have failed at the same time, so that points to a software issue. You might want to think about re-flashing a stock ROM to replace the operating system. I'm not familiar with OTT or MXQ stuff so I can't suggest where to find valid stock ROMs for this or the procedure to flash them, hopefully others who are will comment on reliable sources.
Depending on how much more time and effort you want to put into this, this is a last resort, defeatist option but considering the average retail price of $35 it might be just as prudent to just replace it.