Connections to the server “imap.gmail.com” on the default ports timed out

I have had several business business email accounts for years. Within the last 6 months or so, I keep getting a triangle with an exclamation point next to each of them. When I click on it it gives the following message: Connections to the server “imap.gmail.com” on the default ports timed out -- Cancel or Try Again. Click on Try Again and it does nothing. Close out of email and come back and does nothing, rebut laptop and nothing. Follow some of the instructions given on the Apple Community, and some times it helps, but I am back again to the same issue in not time. This is becoming DAILY and SEVERAL times a day. As a business I can't afford this! I need some help, please! Additionally, even before this began to happen, all my email rules stopped working, "VIP" stopped working, some of my "inboxes" disappeared, some moved from where they were placed originally, and then all mail began going to "Archive." Needless to say, productivity has seriously been affected. I will appreciate any help