调用Mailgun API时Curl遇SSL意外EOF错误求助（仅特定服务器）

在当前Ubuntu 22.04服务器上，使用curl请求Mailgun的EU API时已持续数小时出现SSL错误，相同版本及配置的其他服务器无此问题，已排除curl版本问题，怀疑是证书相关问题。

curl请求命令及错误输出 #

执行命令：

curl -vvv 'https://api.eu.mailgun.net/'

返回错误：

* Connected to api.eu.mailgun.net (34.111.145.192) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
*  CAfile: /etc/ssl/certs/ca-certificates.crt
*  CApath: /etc/ssl/certs
* TLSv1.0 (OUT), TLS header, Certificate Status (22):
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.0 (OUT), TLS header, Unknown (21):
* TLSv1.3 (OUT), TLS alert, decode error (562):
* error:0A000126:SSL routines::unexpected eof while reading
* Closing connection 0
curl: (35) error:0A000126:SSL routines::unexpected eof while reading

curl版本信息 #

curl 7.81.0 (x86_64-pc-linux-gnu) libcurl/7.81.0 OpenSSL/3.0.2 zlib/1.2.11 brotli/1.0.9 zstd/1.4.8 libidn2/2.3.2 libpsl/0.21.0 (+libidn2/2.3.2) libssh/0.9.6/openssl/zlib nghttp2/1.43.0 librtmp/2.3 OpenLDAP/2.5.14
Release-Date: 2022-01-05
Protocols: dict file ftp ftps gopher gophers http https imap imaps ldap ldaps mqtt pop3 pop3s rtmp rtsp scp sftp smb smbs smtp smtps telnet tftp
Features: alt-svc AsynchDNS brotli GSS-API HSTS HTTP2 HTTPS-proxy IDN IPv6 Kerberos Largefile libz NTLM NTLM_WB PSL SPNEGO SSL TLS-SRP UnixSockets zstd

OpenSSL连接测试结果 #

执行证书检查命令：

openssl s_client -connect api.eu.mailgun.net:443 -CApath /etc/ssl/certs

返回结果：

CONNECTED(00000003)
write:errno=104
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 0 bytes and written 320 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)
---

内容的提问来源于stack exchange，提问作者Crack_David