Hello Roland,
On top of what Jeff provided, in order to connect from outside to your SQL Anywhere Engine, you need to add to your connection string the following tcpip parameter which says DoBroadcast=NONE
Example
dbisql -c "UID=dba;PWD=sql;ENG=mydbenginename;DBN=databasename;CommLinks=tcpip{host=ip_address;port=port_number;DoBroadcast=NONE}"
This will allow it to go through.
Thank you,