Halo @ariluna,
Permasalahan cURL error 28 ini disebabkan ada kendala konektifitas dari server hosting anda ke server API RajaOngkir.com. Plugin Woongkir tidak ada melakukan blocking sama sekali.
Umumnya disebabkan oleh masalah berikut:
* DNS resolving (your server is not able to resolve the IP for the third-party domain or at least not in time).
* Firewalls or security modules (e.g. mod_security ) blocking the outgoing request. Your host is not able to “talk” with the third-party server due to unavailable required protocols. This can occur if the server has a recent cURL/OpenSSL but it’s not correctly configured to use TLS 1.2 as SSL procotol.
* Network issues (something at network level prevents your server to reach the third-party server).
Untuk lebih lengkap bisa baca di link berikut:
https://www.samuelaguilera.com/post/curl-error-28-wordpress
Untuk solusinya, saya sarankan untuk pindah hosting provider yang lebih reliable, berikuta contoh kasus dan solusi isu cURL error 28 yang lain:
https://www.ads-software.com/support/topic/curl-error-28-connection-timed-out-after-10001-milliseconds/
Sofyan