SAP RS: Can't connect to RS but can connect to ASE in the same server

What happened?
Can't connect to RS but can connect to ASE in the same server:

C:\SAPRS>isql64 -S RSSERVERNAME -Usa -Ppassword
CT-LIBRARY error:
        ct_connect(): user api layer: internal Client Library error: Read from the server has timed out.
CT-LIBRARY error:
        ct_connect(): network packet layer: internal net library error: Net-lib operation timed out

C:\SAPRS>isql64 -S ASESERVERNAME -Usa -Ppassword
1>

Error message:
Check in the RS log:

I. 2020/04/22 20:34:47. Check the log for error messages from RSSD.
I. 2020/04/22 20:34:47. Message from server: Message: 7412, State 2, Severity 10 -- 'Space available in the log segment has fallen critically low in database 'RS_RSSD'.  All future modifications to this database will be suspended until the log is successfully dumped and space becomes available..

Cause: 
Log space of the RSSD database (of the RS) is full.
Check it using:

sp_helpdb <RSSDNAME>
sp_helpdevice <RSSDLOGDEVICENAME>

Solution:
Add space to the RSSD log:
http://copypastenet.blogspot.com/2020/01/sap-ase-sybase-transaction-log-in.html