Private IP on Wan and public IP on LAN

Hi I have set and Private IP as 192.168.57.158/30 on eth1 GW is 192.168.57.157 and I have bridge To LAN Ports with IP 1.a.b.233/29 which will be the GW to the PC /Router behind the mikrotik. In turns the Router PC with IP 1.a.b.234/29 and GW 1.a.b.233 dns 8.8.8.8 has internet after Nating all src addresses 1.a.b.232/29 to eth1 as output, now any device with 1.a.b.23x/29 on my bridge has internet and can do any thing, also mikrotik is accessible through 1.a.b.233 without any issue. But I can not set NTP client as mikrotik can not ping internet. I have spare public IP I can use for mikrotik besides the GW 1.a.b.233 if it is required, please help me to get internet to the box so I can have my clock correctly set and can update my operating system without using external source.

Can you please help?! Thanks

Very strange design, but try to ping 8.8.8.8 from terminal with your provider’s private IP.