Hello people.
Almost every other time, the periferial devices don’t load on startup.
Only the modem does load.
I mean there’s no option to allow them or not, they just don’t appear.
Please point me to where I might add them manually, instead of having to reboot the PC, every time this happens.
Best regards 
Try to run in dom0 terminal:
sudo systemctl --user restart qubes-widget@qui-devices
Also you can report this but in qubes-issues. This one looks similar:
Hello.
Thank you, but this is the error message I get after that command:
“Failed to connect to bus: No such file or directory”
Regards.
You can fix it like this:
But there must be some problems with your dom0 if you don’t have /lib/systemd/systemd --user process running so there may be more problems that you’ll face.
You can check the logs in dom0 for strings err or fail to check what was the root cause of this issue:
sudo journalctl
I couldn’t find neither err, nor fail using the Terminal\Find feature …
Thanks.