The obsolete Borant travel network, useless for reaching Aryl now that its node is gone.
When Zev describes the attempts to organize a rescue into the Aryl System, she notes that tunnel access has been cut off and that even the old Borant travel system won't work with the node gone. The legacy Borant gates were the fallback option, a holdover from the previous administration of the crawl, and they still depend on the Tunnel Node existing at the far end.
With Aryl's node dark, every route in is closed: no tunnel, no gate, no communication. Rescue of the stranded miners and the surface investigation team is being discussed but cannot actually be mounted.
The obsolete backup travel network that also fails without a functioning node.