Apache已启用HTTP/2但仍以HTTP/1.1响应请求的问题求助

大家好，我最近碰到一个棘手的问题，折腾了好久都没解决，想请各位大神帮忙分析下。

我的服务器环境是：

• CentOS 7系统
• Apache/2.4.34 (Red Hat)
• OpenSSL/1.0.2k-fips
• PHP 7.4.33

我按照相关指南安装并启用了HTTP/2，整个过程没有报错，模块也确实加载成功了，但不管怎么测试，页面始终还是用HTTP/1.1来响应。

我已经排查过以下几个常见问题：

• 已经把MPM从prefork切换到了event，确认这个不是导致问题的原因
• 排除了浏览器缓存的影响，试过清空缓存、用隐身模式访问，结果还是一样
• Apache已经重启过好多次了，确保配置能生效

下面是我的相关配置和命令输出：

核心配置 #

配置文件中添加了：

Protocols h2 http/1.1

SSL协议配置：

SSLProtocol all -SSLv2 -SSLv3

httpd -V输出 #

Server version: Apache/2.4.34 (Red Hat)
Server built:   Oct 11 2022 12:56:44
Server's Module Magic Number: 20120211:79
Server loaded:  APR 1.4.8, APR-UTIL 1.5.2
Compiled using: APR 1.4.8, APR-UTIL 1.5.2
Architecture:   64-bit
Server MPM:     event
threaded:     yes (fixed thread count)
forked:     yes (variable process count)
Server compiled with....
-D APR_HAS_SENDFILE
-D APR_HAS_MMAP
-D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
-D APR_USE_SYSVSEM_SERIALIZE
-D APR_USE_PTHREAD_SERIALIZE
-D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
-D APR_HAS_OTHER_CHILD
-D AP_HAVE_RELIABLE_PIPED_LOGS
-D DYNAMIC_MODULE_LIMIT=256
-D HTTPD_ROOT="/opt/rh/httpd24/root/etc/httpd"
-D SUEXEC_BIN="/opt/rh/httpd24/root/usr/sbin/suexec"
-D DEFAULT_PIDLOG="run/httpd.pid"
-D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
-D DEFAULT_ERRORLOG="logs/error_log"
-D AP_TYPES_CONFIG_FILE="conf/mime.types"
-D SERVER_CONFIG_FILE="conf/httpd.conf"

apachectl -M输出（确认http2_module已加载） #

core_module (static)
so_module (static)
http_module (static)
access_compat_module (shared)
actions_module (shared)
alias_module (shared)
allowmethods_module (shared)
auth_basic_module (shared)
auth_digest_module (shared)
authn_anon_module (shared)
authn_core_module (shared)
authn_dbd_module (shared)
authn_dbm_module (shared)
authn_file_module (shared)
authn_socache_module (shared)
authz_core_module (shared)
authz_dbd_module (shared)
authz_dbm_module (shared)
authz_groupfile_module (shared)
authz_host_module (shared)
authz_owner_module (shared)
authz_user_module (shared)
autoindex_module (shared)
cache_module (shared)
cache_disk_module (shared)
cache_socache_module (shared)
data_module (shared)
dbd_module (shared)
deflate_module (shared)
dir_module (shared)
dumpio_module (shared)
echo_module (shared)
env_module (shared)
expires_module (shared)
ext_filter_module (shared)
filter_module (shared)
headers_module (shared)
http2_module (shared)
include_module (shared)
info_module (shared)
log_config_module (shared)
logio_module (shared)
macro_module (shared)
mime_magic_module (shared)
mime_module (shared)
negotiation_module (shared)
remoteip_module (shared)
reqtimeout_module (shared)
request_module (shared)
rewrite_module (shared)
setenvif_module (shared)
slotmem_plain_module (shared)
slotmem_shm_module (shared)
socache_dbm_module (shared)
socache_memcache_module (shared)
socache_shmcb_module (shared)
status_module (shared)
substitute_module (shared)
suexec_module (shared)
unique_id_module (shared)
unixd_module (shared)
userdir_module (shared)
version_module (shared)
vhost_alias_module (shared)
watchdog_module (shared)
dav_module (shared)
dav_fs_module (shared)
dav_lock_module (shared)
lua_module (shared)
mpm_event_module (shared)
proxy_module (shared)
lbmethod_bybusyness_module (shared)
lbmethod_byrequests_module (shared)
lbmethod_bytraffic_module (shared)
lbmethod_heartbeat_module (shared)
proxy_ajp_module (shared)
proxy_balancer_module (shared)
proxy_connect_module (shared)
proxy_express_module (shared)
proxy_fcgi_module (shared)
proxy_fdpass_module (shared)
proxy_ftp_module (shared)
proxy_http_module (shared)
proxy_hcheck_module (shared)
proxy_scgi_module (shared)
proxy_uwsgi_module (shared)
proxy_wstunnel_module (shared)
ssl_module (shared)
systemd_module (shared)
php7_module (shared)

虚拟主机配置（更新后） #

<VirtualHost _default_:443>
DocumentRoot "/var/www/html"
ServerName ###
ServerAlias www ###
Protocols h2 h2c http/1.1
ErrorLog logs/ssl_error_log
TransferLog logs/ssl_access_log
LogLevel warn
SSLEngine on
SSLProtocol all -SSLv2 -SSLv3
SSLCipherSuite HIGH:3DES:!aNULL:!MD5:!SEED:!IDEA
Include /etc/letsencrypt/options-ssl-apache.conf
SSLCertificateFile /etc/letsencrypt/live/###.ro/cert.pem
SSLCertificateKeyFile /etc/letsencrypt/live/###/privkey.pem
SSLCertificateChainFile /etc/letsencrypt/live/###/chain.pem
</VirtualHost>

测试结果 #

用HTTP/2检测工具测试后，得到的结果是：

HTTP/2 protocol is not supported.
ALPN extension is not supported.

实在找不到问题出在哪了，有没有朋友遇到过类似情况，或者能给我一些排查方向？感谢大家！

备注：内容来源于stack exchange，提问作者qlangiul