Firefox 49 doesn't work with the CWMS Meeting Clients resulting in error 111 when starting.
Workarounds:
Using a Temp meeting client works with Firefox 49
Using different browsers or older Firefox versions.
Even though it is documented that Firefox 47 and older are supported, there is a defect opened for this issue and will be resolved on top of CWMS 2.7 MR1 and 2.6 MR3 (CSCvb47815). ETA for the patch is second half of October 2016.