HTTP / 2 Server Push из Apache за HAProxy

Мне интересно, можно ли использовать функцию HTTP / 2 Server Push за HAProxy. HAProxy 2. + поддерживает HTTP / 2 во внешнем и внутреннем интерфейсе. Я создал простую настройку для тестирования, насколько я могу судить, веб-сервер Apache не отправляет контент, если он находится за HAProxy. Для тестирования я использовал клиент nghttp.

Конфигурация HAProxy 2.1 Backend

backend test-http2-push
server localhost 127.0.0.1:81 proto h2 check

Конфигурация HTTP / 2 Apache 2.4.38

H2Push          on
H2EarlyHints    on
Protocols h2c h2 http/1.1
Header set Link "</push1.css>; rel=preload; as=style"
H2PushResource /push2 critical 

Прямой запрос бэкэнда Apache

nghttp -ans http://test-http2-push.development.vm:81

ответ

***** Statistics *****

Request timing:
  responseEnd: the  time  when  last  byte of  response  was  received
               relative to connectEnd
 requestStart: the time  just before  first byte  of request  was sent
               relative  to connectEnd.   If  '*' is  shown, this  was
               pushed by server.
      process: responseEnd - requestStart
         code: HTTP status code
         size: number  of  bytes  received as  response  body  without
               inflation.
          URI: request URI

see http://www.w3.org/TR/resource-timing/#processing-model

sorted by 'complete'

id  responseEnd requestStart  process code size request path
  13     +2.07ms       +107us   1.96ms  200   2K /
   2     +2.30ms *    +1.70ms    594us  200  114 /push2.css
   4     +2.31ms *    +1.73ms    574us  200  114 /push1.css

Звездочкой отмечено нажатие на сервер.

Запрос HAProxy:

nghttp -ans https://test-http2-push.development.vm

ответ

***** Statistics *****

Request timing:
  responseEnd: the  time  when  last  byte of  response  was  received
               relative to connectEnd
 requestStart: the time  just before  first byte  of request  was sent
               relative  to connectEnd.   If  '*' is  shown, this  was
               pushed by server.
      process: responseEnd - requestStart
         code: HTTP status code
         size: number  of  bytes  received as  response  body  without
               inflation.
          URI: request URI

see http://www.w3.org/TR/resource-timing/#processing-model

sorted by 'complete'

id  responseEnd requestStart  process code size request path
 13     +2.07ms       +138us   1.93ms  200   2K /
 19    +10.36ms      +2.09ms   8.27ms  200  114 /push1.css
 21    +10.92ms      +2.09ms   8.83ms  200  114 /push2.css

Нет сервера.

Журнал Apache показывает, что HAProxy говорит HTTP / 2 с серверной частью:

127.0.0.1 - - [25/Mar/2020:18:26:52 +0100] "GET /push1.css HTTP/2.0" 200 114 192.168.56.1 forwarded by: 127.0.0.1
127.0.0.1 - - [25/Mar/2020:18:26:52 +0100] "GET /push2.css HTTP/2.0" 200 114 192.168.56.1 forwarded by: 127.0.0.1

Я что-то упускаю? Я ценю любую помощь.