cst calculation unstable

i believe you've surely met this error:
"The calculation seems to be unstable!
Consider reducing the value for the stability factor in the solver specials options or reducing the PBA fill limit in the automesh properties"
i met this several times in the "Automesh adaption", when the simulation runs into the pass 4, e.g.
What's the reason for this?
It seems the suggested two solutions are not that effective.
Thank you!

could someone help offer some suggestions?

Yes, i often meet this problem.
I think It can come from some wrong in solver setting or meshing properties, or something like that!
Last time , i had solved two these "unstable" problem , but i don't know what is your actual case?
Can you tell more detail about the port signals information and the energy convergence condition?
I am willing to share y experience!

hi Khanghang,
actually i feel this warning is not linked to a single structure but a general problem.
i shall give you more information about my structure later.
Many thx!