This is not really a question, more of an answer. I know many of us have sporadic problems with SMTP (working one day but not working the next) and I thought I would simply let people know of my solution. the issue seems to be that I use a VPN (Windscribe) which sometimes (and for no obvious reason) seems to block my outgoing emails. I'm sure a more permanent solution could be arranged, but I find that if I turn my VPN off, then SMTP works fine. If I then turn it back on again, it is still working fine. So providing I'm happy to send at least one email using my home IP address, there is no real issue.
I only found the simple solution (after multiple attempts to reconfigure my accounts) by accident . I'm guessing there are lots of other reasons why SMTP doesn't work, but for anyone using a VPN this "turn it off and on again" solution may ease frustrations.
