Yes, if router supports 'bandwidth (or, traffic) shaping' feature.

An op amp can have a very large gain, but a limited bandwidth. If you decrease the gain, you can increase the bandwidth.

There is a relation between transmission media and bandwidth. The transmission media cannot exceed the amount of bandwidth available. The transmission of media is limited to the bandwidth.

probably

(the carrier frequency +- the maximum frequency of the pulse train)/(the carrier frequency)

but pulses have a lot of harmonics

Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the bandwidth. The signals ranging within the upper limit & lower limit are called bandwidth signals.