Just see the Flint 4.0 release2 beta firmware released, however it complains “Incorrect firmware format” through local upgrade?
When you upgrade to 4.0, pls the .img file and upgrade in uboot.
I see, thanks. ( I think the download page should mention about this.) 
Yes. Hope this post helps new guys.
It’s avesome after the firmware upgraded as dramatic improve on the OpenVPN speeds but the smartphone app is not supported the version.