I'm playing an Abjuration Wizard. I'm currently planning & building an awesome wizard fortress using the Mighty Fortress Spell (XGtE), and all of the other semi-permanent spells I can think of. Mordenkainen's Private Sanctum, Guards and Wards, Warding Glyphs and Symbols on every wall, you get the idea.
I'm running into trouble with teleportation. I really want to have a permanent teleportation circle in my fortress - that way I can always, reliably travel there, and bring a big group with me if needed. However, I want that teleportation circle to be the only way into the fortress. All of my traps and wards do me little good if someone can simply dimension door into the middle of my fortress.
The only spells I can see that block teleportation (like Mordenkainen's Private Sanctum or Forbiddance) seem to block all teleportation effects without restriction, which would mean that I wouldn't be able to use the teleportation circle. This runs counter to my purposes as I place really high value on having that teleportation circle active. I'm looking for an effect or spell that can block most/all teleportation into my fortress, but allow me to use my circle. I'm okay with others using the circle if they know the sequence, as that will be a closely guarded secret and I can heavily trap the circle room.
Is there any way in 5e rules to limit teleportation magic in an area (in this case, a 50x50x30 foot keep) to a single teleportation circle?