Full Tunnel via Zerotier Issue Using Unbound and NAT

[mush2020]

I'm testing Full Tunnel by allowing default route in ZT network to route all my external devices internet traffic via Opnsense zt interface. Internet works well by using Google DNS
 0.0.0.0/0 via 192.168.194.250

But as soon as i enable Firewall rule and NAT Port forwarding
ZeroTier   TCP/UDP   *   *   ! ZeroTier address   53 (DNS)   127.0.0.1   53 (DNS)   Redirtect DNS to Local

Internet either slow downs or web page not reachable.
In fact i want stop using all other DNS, except Unbound for ZT

For internal network all works well.

Currently tested with IOS device with latest ZT 1.6.1

Anyone can assist to fine tune the configuration in Unbound or NAT or FW rules.