"Just a Flying Router"
This is... not the half pound plastic wifi router in your house.
I don't think there are firm numbers out yet, but the speculation I've seen is that bandwidth on a Gen2 is ~150-200 Gbps. A Cisco ASR 1000 series, terrestrial router with that kind of bandwidth weighs in at 184lbs.
That assumes fans for cooling. If they have to do a liquid cooling system with a radiator to reject heat to space - well that's more weight.
If they harden it for spaceflight, that's more weight.
So the router is already using up about 10% of the stated weight, and it's not even powered yet.
The high end ASR 1000 draws 4000 Watts, so that's about 260 square feet of rooftop solar panels (presumably aerospace panels are more efficient, but I don't have those numbers handy.)
Our mental image of the internet is some ephemeral cloud, but it turns out that it's made of cold, hard (heavy) infrastructure.