reposting my response from
the first version of this thread
the main problem is speed. our real world internet works because it is so small. the information, which moves at the speed of light, is only seconds away from anywhere.
in a space opera setting, the speed of transmission will limit you.
for example, in phase world, FTL communications move at 200 ly/h. meaning that in one hour, a message can cross 200 light years. instant communications can be obtained within a solar system, but communicating between solar systems requires messages to travel for minutes to hours (one way) even for the nearby stars. communicating across the galaxy will take years.
think about it like this. a solar system would have a network as quick as our internet.
but sending messages to other stars is like sending messages to Mars or jupiter in our world. it takes several minutes for the signals to reach the location. the delay between sending off a request and getting the information back would be 2x the time it takes the signal to get their (there and back), plus any time needed to process.
trying to surf the internet of these worlds would be like surfing our internet on a 1k dialup modem. it would take minutes to load each page, if not longer.
more likely, each solar system has a seperate 'net, and they are not connected.
there are canon attempts to make a galaxy spanning instant comm net. but none work well. they either rely on obscure technologies (ansibles, for example), or on rare materilas (psi-crystals found in the ruins of a dead race, for example)