Before or while creating a model, you can specify that only right-angled connection alignments are permitted or that both right-angled and straight connections can be drawn.
Procedure
Right-click in the model background, and select Properties.
On the Selection tab, enable Format > Connections.
Enable the New connections only right-angled check box if you do not want to use diagonal connections. Disable the New connections only right-angled check box to also use diagonal connections.
Enable the Spacing between connections and objects check box if you want there to be a slight distance between the connections and the object, rather than the connections being attached to the object directly.
Click OK.
From now on, you can create new connections with the specified connection alignment.
If you want your setting to also apply to future models, you can change the option settings for connections.