Guide to Find a Specific Planet
Do you know if the planet is in the same galaxy as you?
In the Discoveries list of systems and planets you can Waypoint mark the system (star) containing the planet you want to reach. The tool tip to mark a waypoint should be displayed when you hover over the system with your cursor.
On the Galactic map you can then use the filter to display the blue waypoint line to the destination. Follow the line, ‘warping’ from star to star to reach the waypoint marked system.
If currently you see a green line you may have a mission line selected as the filter. The mission you want currently selected as the focus must be active in the options Log. The mission may have been collected in another galaxy or possibly you have travelled through a black hole and are now a very, very far away from the destination. Also you may even have travelled very far by using the Anomaly doing missions. In any scenario you need to get back to the correct system to do the mission or reset the mission to a nearby system. The mission also has tool tips which can prompt to do a reset or abandon mission. If you do abandon missions they will respawn at some point.
If the system and planet are in a different galaxy then you can NOT set a waypoint mark in the discoveries list until you return to the correct galaxy. If the system is likely to be in Euclid (the first named Galaxy) then simply return to Euclid either by using the Anomaly teleport, a home base teleport, space station teleport or even a pirate restricted teleport. Look for a space station in the correct galaxy to return to. Other galaxy names are usually displayed under the space station icons in the list.
Once you have the filter correctly set to either the mission line (often green) or marked waypoint line (blue) and are in the correct galaxy, then it is still possible you could still be a long way from the destination and this would be shown by a solid line (the extent of how far your star ship can jump in light years). plus additional calculated distance shown by a dotted line that will eventually reach the destination.
A decision would need to be made to decide to reset the mission closer to your current location or abandon the mission to restart it. However if you know any space station in the teleport, already near the planet destination you want to reach, then return to that nearby system space station and then check the galactic map, with the waypoint filter or mission selected to see how close you are.
To return to any planet directly, without star hopping, you can also use a Portal Glyph address that you know. However the same galaxy restriction applies, you must be in the correct galaxy when entering the portal address at a Portal gate teleport, to be sure you arrive at the correct star when exiting the gate.
If you happen to have a screen shot of the planet in question, taken with photo mode, then you may already have a portal address displayed on the bottom left of the picture. It must be used in the correct galaxy and entered at a Portal teleport gate that can be found with a the help of a map, purchased from the Cartographer in any regular space station. The map can locate Ancient Monoliths on a planet, that in turn will lead you to a Portal teleport gate. Ancient Monoliths can also be found indirectly using exocar scanners. Ancient Monoliths require interacting twice, once to answer a question correctly and second to reveal the Portal Teleport Gate location on the planet.