One thing about the forum is that is gets me to thinking on what might be done using the Cepheus Engine for star port changes. My Out Rim sector has no planets that have a very high population, so the star ports have changed. There are no High Ports, as they are too expensive to build and too hard to defend. Unstreamlined ships have no choice but to land passengers and cargo by space lighters, unless the planet has a satellite which has a vacuum. Then you still have the cost of getting the passengers and cargo from the satellite to the planets. Passengers are not too bad, but cargo, especially a lot of cargo, is a major headache. The result is that most ships are streamlined.
Class A ports can build military ships, as well as civilian ships, in private building yards. They do require a population that is in the tens of millions, however. A naval base, not "Wet Navy", can build military ships as well, generally faster and cheaper, but will not build for private clients or other planets. The Naval Base can build at a slightly higher Tech Level than the civilian builders.
Class B ports can build civilian ships, but lack the expertise to build military ships. I should add that military ships are not just heavily armed civilian ships, but have some extra wrinkles. They also cannot build ships larger than a 1000 Traveller dTons, but can build one Tech Level higher than the planet's Tech Level if they import components. That does add to the cost.
Class C ports cannot build ships, but can supply refined fuel, and handle most repairs and annual maintenance. If a major repair is needed, then the necessary parts are imported. They do have reasonable accommodations for passengers and cargo, and will have a few brokers available. It might take more than a week to line up cargo and passengers however.
Class D star ports can supply unrefined fuel and small quantities of refined fuel if pressed. As they are frontier installations, do not expect to be in and out in a week. As for caterers to supply pre-packaged meals, forget it. Your Steward is going to have to know what and how to buy, and then prepare the food from scratch. Brokers are few and far between, so your Cargomaster is going to have to come up with the cargo to lift off with, as well as sell the cargo you brought in. I am working on the idea of a Trader's Guide to the Sector, giving hints as to what works and what does not.
Class E landing spots means that the Rim Scouts have put a beacon on a safe place to land, which has access to water. Beyond that, there may or may not be anything else there. If there is a small settlement there, they probably will not shoot on sight, but might not be exactly accommodating either. As for food and life support supplies, you are going to need to get creative, or have a ship designed for frontier trading, with the ability to carry a couple of months worth of life support supplies.
X Class star ports mean one of two things. Either the Rim Scouts have not gotten there yet, or at least one ship or crew went missing on the planet. Those are the really interesting ones, if you do not mind maybe dying. Now, recovering a Rim Scout derelict does get you a ship under the sector salvage rules, and the Rim Scout "Scouts" are not the typical Traveller ones. They run more like 200 to 400 dTons.
Note, this is what I am thinking of, but it is not cast in collapsium as yet, or even high-tensile strength steel. More like a good Edam or Gouda cheese.