Cannot access an HPE OfficeConnect Switch 1820 24G J9980A via telnet when using PuTTy
The HPE 18xx series don't support telnet or SSH, just HTTP/HTTPS. Their lowest, fully managed series is the 2530; 2xxx have complete management. Some 19xx have a minimal console interface.
You can obtain a command line interface to the switch by using this set of Python-based scripts.
They seem to have some author-specific functionality embedded in them, so handle with care and be prepared to tinker with them.