The very limited available space on the M200 does not allow us to add many certificates to the list.
Indeed, until recently it was not possible to disable "Only accept trusted certificates". However, this has recently fixed and I can send you a test version (v126.96.36.1994c) if you would like to verify how it works for you. Please let me know if you would like to try it out, and I can send you an email with the link.
it would be very nice of you. I would test the new fw right off.
I have sent you the test version.