Why do you think conductivity decreases with dilution?

Definition from Wikipedia: Molar conductivity is defined as the conductivity of an electrolyte solution divided by the molar concentration of electrolyte.

There are two types of electrolytes: strong and weak. Electrolyte is salt mixed in water. Strong electrolytes will usually undergo complete ionization, and therefore they have higher conductivity than weak electrolytes which undergo only partial ionization.

Because strong electrolytes undergo complete ionization, dilution has minimal impact on molar conductivity.

For weak electrolytes (i.e. incompletely dissociated electrolytes), however, the molar conductivity strongly depends on concentration: The more dilute a solution, the greater its molar conductivity, due to increased ionic dissociation.

The above means that as weak electrolytes are diluted further, they undergo more ionization increasing the conductivity of the electrolyte.

For example, acetic acid has a higher molar conductivity in dilute aqueous acetic acid than in concentrated acetic acid.

Sources:

https://en.wikipedia.org/wiki/Dissociation_(chemistry)

https://en.wikipedia.org/wiki/Molar_conductivity