having odd derailment issues (trainz 2019)

So i got a freight train together on one of the UMR routes and when it was setting out and nearing the top speed of the area all the sudden a "excessive acceleration" warning pops up. This is normally unimportant, i play in "easy control" and AI mode most of the time with the arcade derailment setting. However when it popped up a car derailed in the middle of my train, with all cars behind it rapidly derailing with it. i reloaded the save, used player and AI control but nothing helped, every time i neared the top speed of the area, a derailment occurred with the exact same car causing everything behind it to go down the toilet. I have no clue whats causing it, i dont play with the accurate controls mode and this is not usually a issue. Does this have to do with the route? or is their something wrong with the train?

There are a couple of things here that I can think of.

It could be related to your engine or engines pulling the freight. It could be the coupler force is too strong at that point of the train causing the train to break a coupler and derail. This can be caused by climbing a steep grade and pulling too hard. Try slowing down and see if that works, and if it does, keep your speed steady and slow through this area and increase the speed later on at another point.

It could also be that you don't have enough pulling power. Try adding more engines in and see if that helps, or try different engines.

And finally it could be the car its self. I had an issue at one time with some small beer can type tank cars causing random derailments as the train exited portals. After replacing those with something else, that problem went away.