"Sorry, could not teleport..."

"..you do not have access to the teleport destination."

My sim is online, as the map shows, but I can't get to it at all, none of the various locations there I have landmarked will work.

What causes this when the sim is not listed as off line?

"You do not have access" would mean that you are not allowed on that SIM. Either Public access has been turned off.... Access has been restricted to only certain people... or you have been Banned from that SIM.

If it is Your sim or You have estate controls, You may have clicked the "no direct teleport" button in the estate controls. I have had two managers do this in the past and the only solution, if the island stands alone, is to have a Linden come out and un-check that option.

If the island does not stand off by it's self on the gird, try tpin to the one next door and walk across.

I've had that happen before when trying to get to a place I know I have access to (like home lol) and often times I'll just tp to a nearby location and walk or fly over.

I have to believe it's some kind of occasional glitch because it's happened often enough to me over the last 2 years....it does also happen if an area is closed off to the public, as stated.....maybe for renovations or whatever. But....I've never been banned or booted out of a sim for any reason so when ever I see that I figure it's closed temporarily...or it's a hiccup.