we should be able to update the cmux program so that it can workout if the SARA-R5 is in CMUX mode… ill get back to you on this.
There other issue is strange. There is a little delay when accessing or leaving the virtual serials, but it should <1 second, this is normal.
What Pi are you using?
Is it overclocked?
Do you have anything else attached or running?
Mark --OzzMaker.com --