Get is often used in colloquial English to form a kind of passive: get disconnected means the same as become disconnected.
In general, this passive does not mean the same as the corresponding active (eg get eaten means the same as be eaten, which is not the same as eat).
Some verbs have what is sometimes called a 'middle' sense, in which a formal active has almost the same meaning as a passive; so The rice got cooked means nearly the same as the rice was cooked and the rice cooked. But this depends on the particular verb (and sometimes on the particular meaning of the verb, so you can do it with cook meaning process by applying heat in some way, but not with cook meaning prepare a dish or a meal).
Disconnect is marginal: I wouldn't say The internet disconnects frequently, but I think some people might.
So the simple answer to your question is that get is freely used to create passives in colloquial English, but many people would not regard it as appropriate in formal writing.