I am in the situation of this user. https://stackoverflow.com/questions/49308744/telegram-bot-ssl-error-ssl-...
When Virtualmint let's encrypt renew the certificate automatically Telegram does not consider SSL valid. To solve the problem I have to delete the 5 files (ssl.ca, ssl.cert, ssl.combined, ssl.everything, ssl.key) and ask let's encrypt for a new certificate.
At that point everything works.
Suggestions to make the certificate that virtualmin let's encrypt automatically generate is also valid for Telegram?
Thanks for the help a warm greeting