Mac OS cannot connect to Exchange 2016

all of a sudden any mac cannot connect or verify on prem exchange 2016 accounts - any other device including ipad, iphone, windows, webmail can authenticate and connect no problem, just mac's using either mail or outlook, both dont work.  unable to verify account.  nothing has changed in the configuration except that the ASA firewall was replace but has same config as before and all other devices and webmail works as normal.  any ideas?  is this an IMAP issue?