I have the very same problem - turris MOX P-A-B with WLE900VX and TOS HBS v4.0.3 installed.
Today my WiFi failed the first time after a uptime of ca. 8 days:
I generated a log and will send it to tech.support@turris.cz
If this happens again I will try to replace Candela Technologies-drivers/-firmware with normal one.
Do you all experience still the same problem?