I am facing the following problem. With regard to the Sap logon configuration (https://erproof.com/basis/free-training/sap-logon-configuration/), in step three, every time I fill in the SAP router string, after accepting the capital /S/ in the SAP router string, it chanches to a lower case letter.
I think that this is the explanation that if I want to connect to the server, the hostname is unknown.
The definition of /S/ is stand for Host port. It’s optional and if not available it will use the default port 3299.
I’m not really sure how you input it, but yes it should be Upper cased.
May be try to type it first in a notepad then copy paste it to Router string input,
or sometimes the issue can come from the SAP GUI installation, try reinstall it with an updated version one.