Some warp routes are not open from the start. They stay locked until you complete a specific mission. If your fleet cannot plot a course somewhere you expect to reach, check whether the path needs a mission first. Upgrading warp range does not fix a mission-locked route. The list covers Augment, Critical Path, Voyager, Mirror and G5 and G6 superhighway routes. Below, each mission is named first and followed by the routes it opens. You can check each mission's details on the Missions pages of stfc.space.
These four missions come from the Augments Mission Chain (Uncaged storyline). Retrofit opens Rigel to Rainsford, Rainsford to Lydan, Rainsford to Raddan, and Lydan and Raddan to Tera Lara. Volatile Combinations opens Tera Lara to Rona Tan, Rona Tan to Gealan and Kor Na Ron, and Kor Na Ron to Terazon X31 and Paradane. Recuperation opens Kor Na Ron to Duriana, Duriana to Vellamo and Ifrea 3, and Ifrea 3 to Olassa. Receding Light opens Ifrea 3 to Orda 877, Orda 877 to Ilmatar, and Ilmatar to Yarda 74. Three connectors are picked up in-system. Autopilot: Duriana (on Goqinug in the Duriana system) opens Rona Tan to Duriana. Autopilot: Yarda (on Tessen in the Yarda-74 system) opens Duriana and Quvolis to Yarda 74. Autopilot: Tera Lara (on Tera Lara) opens Eojur to Tera Lara.
Now and Then, Part 9 opens Talmir 86 to Ambit. You find it in the Holodeck, in the TOS section. These missions come from the Critical Path storyline. Dark Space opens Haakona to Garadius, Bolarus to Fibona, Balduk to Ty'Rall, and Rek'Sgar and Weima to Beta Sector. Take Arms Against an Empire of Troubles III opens Hauge to Kalalisko. The G5 Romulan Missions also list it. Twists and Turns opens Umxheli and Ash-tor to New Vulcan. Forwards is Backwards opens Nikola to Singularity Apex.
The Delta Quadrant corridor opens through Voyager Missions. Each opens one hop. Voyage to Velixys opens System J-25 to Jiiny, Jiiny to Malon Vortex, and Malon Vortex to Velixys. Voyage to Illusys opens Bartu'shakai to Illysus. Voyage to Asil-A opens Velixys to Asil-A. Voyage to Bartu'shakai opens Asil-A to Bartu'shakai. Four more missions open the smaller hops: Commiseration (Commiseration to Ba'Neth), Waste Management Part 3 (Mnea to Think Tank), Entanglement Part 8 (Ba'Neth to Hasak) and Silver Scar Part 2 (Tugaash to Nygea). Mirror Independent Space opens through the Mirror Independent Space Unlock mission in the Mirror Missions: G5K1 to Mirror Romii, then Mirror Romii to Mirror Nausicaa.
The higher-level superhighways unlock mostly through G5 and G6 mission sets and research trees, not story missions. The G5 Superhighway Missions give three. Baelosian Space Superhighway opens Ty'Rall to Garadius and Farana, Draumen to Fibona, and Garadius to Fibona. KSG Space Superhighway opens Erendari to tIn jIb. Immortal Space Superhighway opens Remme to Dela and Dela to Farana. The Combat Research Tree gives the Origin Sector Superhighway: Endriz to van Vlerken, Ester to Erendari and Orasi-18, Orasi-18 to Rua, Ty'Gokor to Ester, and Brestant to Orasi-18. The G6 Build Missions give OPS61, which opens Xenris to Nerokira, Xor'Na'Tin to Shaz, Kinatal to Omega Rura, and Blum to Daz. The G6 Research Tree gives FED Superhighway Unlock (Har-52 to Lorraine, Bess to Endron Beta, Solas Astra to Ishka'du), ROM Superhighway Unlock (Illuminia to Zeta Kan, Gratia-3 to Cortazar) and KLG Superhighway Unlock (Memorium to Tesdach'koH). Two more routes: What We Lost (G5 Klingon Missions) opens Magnamia to batlh'lI juH. ...Something Stares Back (G5 Critical Path) opens Vacuum Epicenter to The Void.