Premier mail shield appears to be blocking gmail through outlook

Hi all, my wife runs her gmail account through Outlook 2016 on Office 365. We have Avast Premier also running which appears to be blocking connection to the gmail server. I added my hotmail account to her Outlook which sends and receives with no problem. It’s been fine for 2 years, suddenly yesterday this problem appeared. Asus Windows 10 machine. Haven’t changed any settings within Outlook, gmail password etc… correct. If I disable Avast, all comes good, send and receive - enable Avast again and Outlook gives error. Seems to be specific to gmail. Anyone else had this issue and how to resolve it? Thanks in advance.