How to fix "dead' trade route?

One of my trade routes (Taramba) was looking "broken": when I selected it, instead of typical information about incoming and outgoing trade routes, I saw this:

Playing with another Trade Hub (Whaskar, which was functioning properly), I've connected it to this broken one. Now Whaskar is 'broken' too and I can't connect it to my trade network. When I select any of the 'broken' trade hubs and right click on another functioning one nothing happens...

What's wrong? Why I can't connect my trade hubs to the trade network?

I've tried to demolish those 2 starports and build them again... - did not help. After they were built they are not connected to the trade network and I can't connect them by right-clicking.

In fact, Meskeban is connected to Taramba, and Taramba connected to Sidyr, but Sidyr has no connection either.

Solution 1:

So, once I realized that my 'dead' trade hub is connected to a system without a startport, the solution was to:

1. Build a starport in that system
2. Change the trade route of the 'dead' starport to the working one
3. Downgrade this recently built starport

Hope this will help somebody else.