I doubt demons are restrained as we see their effects today.(They hold public office in our government!) Further, did not Christ cast out demons which would hardly be possible if chained in hell. Just a thought.
I did not say ALL demons are restrained. They are legion.
Specifically, in the bible, the 1/3 of angels that followed Satan are currently restrained and will be let loose during the end times (as will Satan himself after the 1000 year reign of Christ — which of course is AFTER the Tribulation).
Lesser demons are still running rampant, as is Satan himself who is the “God of this world”.