You can't actual demonstrate that something is actually true as having reality independent of mind as something being in itself and you know what that is as being in itself.
Example: If sighted and reading this on a monitor, you don't have access to knowledge of the monitor in itself.
Nobody have solved epistemological solipsism.
https://plato.stanford.edu/entries/other-minds/
Solipsism and the Problem of Other Minds | Internet Encyclopedia of Philosophy
Now I do believe that you exist, but I can't show that to be true. It only appears to work. Now for truth you get this:
It means that in practice your claims of reality are unprovable and thus not true beliefs.
Truth is a cognitive and psychological state of mind, which only appears to work. It is a form of pragmatism, where you test your beliefs in regards to your experiences, but you don't have access to the true metaphysical and ontological status of objective reality in itself.
So if you claim that you know the actual truth of objective reality, I would like your reasoning. Not just claim it, but use rational justification.
BTW you also have to tackle Agrippa's Trilemma and Protagoras' "Man is the measure of...".