I just received a brand new RT-AC86U today. Before changing any settings, I went into "manual" mode in the web GUI and selected "upload". I am using Asuswrt-Merlin 384.7 and my sha256 checksum matches, so my file is not corrupt. However, I get an error in the web GUI: "file format or path is invalid!".
I moved the file into the downloads folder, so there should not be an issue with the path.
filename & checksum:
a1823355dce8139d287379b91a61edef6f5e047c2357e70271250e66f78eae3e RT-AC86U_384.7_0_cferom_ubi.w
Is anyone else seeing this?