@mmtrade yeah, that's the problem. IPv6 is not working on the server. Can you also try ping6?
$ ping6 ipv6.api.cloudron.io PING ipv6.api.cloudron.io (2604:a880:800:10::b66:f001) 56 data bytes 64 bytes from prod.cloudron.io (2604:a880:800:10::b66:f001): icmp_seq=1 ttl=45 time=122 ms 64 bytes from prod.cloudron.io (2604:a880:800:10::b66:f001): icmp_seq=2 ttl=45 time=235 ms