Audio drops at random while i am streaming.

[DrFunkySpoon]

Hello - I am streaming on OBS using a Presonus 1810c audio interface. Everything works well except every 20 minutes or so the audio completely drops out. The only way I can seem to get it working again is to quit OBS and restart it, which is pretty bad during a livestream with an audience.
Can anybody tell me how to fix this?
Many thanks!