If you have two attacks for any reason, using a net clearly prevents you from using any more. Suppose you have a trident and you attack with your trident first, though: can you swap to your net for your second attack (assuming swapping weapons like that is allowed as the free object interaction) and get both off anyway?
Yes, I know nets are not very good.
From the PHB, page 148:
When you use an action, bonus action, or reaction to attack with a net, you can make only one attack regardless of the number of attacks you can normally make.
This is a deterministic statement. Whatever action you use to attack with a net can only be used to make a single attack (the attack with the net). Order doesn't matter here. Attacking with the trident bars you from attacking with the net with one of your other attacks.
If the rule for nets said something along the lines of "Attacking with a net prevents you from making any further attacks with the same action.", then you could attack with another weapon, then attack with the net. As phrased, this isn't allowed.
