Next time, you should consider creating a new topic, then.
- Did you check entropy, if so can you post the results?
If entropy is low, have you attempted installation of haveged??? 
@farmwald, BTW, https://omnia.turris.cz/en/ states:
Apart from that, Turris Omnia also has SIM card slot, RTC with battery backup, crypto chip for secure random number generation, dimmable RGB LEDs and more.
Are you sure there's not a device at /dev/hwrng
Do you see random data if you enter:
cat /dev/hwrng
If so, you can install rngd and edit /etc/config/system:
config rngd
option enabled '1'
option device '/dev/hwrng'