Servius, Commentary [Aeneid 1.170]
Some people have it that a question arises from this passage. If Neptune favors the Trojans, why did Aeneas not come to Africa with all of his ships? But Neptune, after he sensed that the storm had arisen, was able to liberate the Trojans from their danger, though he was unable to change things which happened before that. For it is agreed that the ship of Orontes perished with all of his companions. The economy of the book would have perished itself, had Aeneas arrived with all of his ships. They want, however, the seven ships to be accounted for such that one is Aeneas’, three were freed from the rocks by Cymothoe and Triton, and three were rescued from the sand banks (which Neptune rendered navigable), while the others were just dispersed. We read later that they were driven to the shore of Africa. Naevius gives a new account of it in his Punic War, when he says that Aeneas had one ship which Mercury made.
huc septem Aeneae c. n. quidam volunt hoc loco quaestionem nasci. si favet Neptunus Troianis, cur cum omnibus navibus ad Africam non pervenit Aeneas? sed Neptunus postquam sensit tempestatem commotam, potuit de periculo liberare Troianos, ante facta vero mutare non potuit. nam et Orontis navem cum omnibus sociis eius constat perisse: et simul libri oeconomia perisset, si Aeneas cum omnibus navibus pervenisset. volunt autem septem naves ita interim colligi, ut una Aeneae sit, tres de saxis a Cymothoe et Tritone, tres de syrtibus, Neptuno syrtes navigabiles faciente, liberatae sint, reliquae tantum dispersae sint, quas paulo post legimus ad Africae litus adpulsas. novam tamen rem Naevius bello Punico dicit, unam navem habuisse Aeneam, quam Mercurius fecerit.