I have been testing various DVB-T sticks and I have good results with the following:

Nova T and Playstation twin tuner using dib0700 drivers.

Sundtek DVB C/T stick via Sundtek control centre works well.

Leadtek Dongle gold using A9015 drivers I had trouble the box recognising ill have to look into this further.

On another note I noticed after I used the Sundtek stick it upset the dib0700 drivers so I advise to use one or the other.

This is the only Openpli 4 image for Dm800 that for me that any USB DVB tuners work so I am very happy so far with the work that has been done by the team