Don't go for a Free VPN for Firestick, that's my humble request there. Free VPNs will not help you unblock everything and neither will it be fast enough. I came across a VPN that cost $60 to $65 for 2 years plan, that's around $2.7 a month.
Try using a paid one, rather than a free one.
Try using a paid one, rather than a free one.