I have strange issue on my server

Hello, everyone
I believe all is well.

I have one server on digitalocean, it was working fine. But two days ago, for security, I enabled firewall with sudo ufw enable and enabled http and https. After that, I disabled it with sudo ufw disable command.
But after that, it seems to have problem on server. My website tries to get some data from API endpoint using GET method. But unfortunately, I get this issue:

I think, it is related to firewall.
Please help me to fix this issue ASAP.
Thanks

Paystack has enabled enhanced security for their API. You’ll have to contact them regarding their security settings.