I have a 2+ gw solar station in orbit but its limited to the throughput of only one interlink despite the presence of 6 on said platform and 9 on the planet.
Do you have any local generation on the planet itself? It would be prioritized for consumption over interlinks due to accumulator priority. If that doesn't account for your difference (and multiple interlinks are visually indicating that they're paired), let me know and I have one idea I could try.