Can't make outbound connection to specific domain

[melloman]

Hi,

Suddenly today I have been unable to perform a CURL command to api.stripe.com. I am able to curl to example.com (both http & https).

This is what happens on the SSH command line:
curl -v https://api.stripe.com/healthcheck
* About to connect() to api.stripe.com port 443 (#0)
* Trying 52.62.14.35...
* Connection timed out
* Trying 13.55.5.15...
* After 86364ms connect time, move on!
* Failed connect to api.stripe.com:443; Operation now in progress

If I disable the CSF firewall in WHM, the api.stripe.com curl command connects correctly,

I've tried clearing the block list, disabled LF_SPI. Nothing apart from completely disabling the firewall or whitelisting all the IP addresses associated with api.stripe.com will fix the issue.

Does anyone know what the issue could be?

[melloman]

Just further to this, I'm now finding that emails are coming through to the server either. Same thing, disable CSF and emails come through.

I've never had this happen in the 4 years I've had the server. Could it be that the CSF files are corrupt?