HTTP/1.1 404 Not Found Error

When trying to connect the plugin to my Piwik I get a 404 Not Found error. I know the url is correct. Could this be a problem caused using HTTP2 on the server that Piwik is installed on?

Here is the error log from the test script:

WP-Piwik 1.0.15
Mode: http

Test 1/3: global.getPiwikVersion

bool(false)

array(2) {
  [0]=>
  string(308) "HTTP/1.1 404 Not Found
Date: Wed, 14 Jun 2017 16:58:41 GMT
Server: Apache/2.4.25 (Unix) OpenSSL/1.1.0f mod_fcgid/2.3.9
Vary: accept-language,accept-charset
Upgrade: h2
Connection: Upgrade
Accept-Ranges: bytes
Transfer-Encoding: chunked
Content-Type: text/html; charset=utf-8
Content-Language: en

"
  [1]=>
  string(155) "https://www.home.zgaah.net:915/piwik/?module=API&method=API.getBulkRequest&format=json&urls[0]=method%3DAPI.getPiwikVersion%26idSite%3Dn%2Fa&token_auth=..."
}

Test 2/3: SitesManager.getSitesWithAtLeastViewAccess

bool(false)

array(2) {
  [0]=>
  string(308) "HTTP/1.1 404 Not Found
Date: Wed, 14 Jun 2017 16:58:42 GMT
Server: Apache/2.4.25 (Unix) OpenSSL/1.1.0f mod_fcgid/2.3.9
Vary: accept-language,accept-charset
Upgrade: h2
Connection: Upgrade
Accept-Ranges: bytes
Transfer-Encoding: chunked
Content-Type: text/html; charset=utf-8
Content-Language: en

"
  [1]=>
  string(232) "https://www.home.zgaah.net:915/piwik/?module=API&method=API.getBulkRequest&format=json&urls[0]=method%3DAPI.getPiwikVersion%26idSite%3Dn%2Fa&urls[1]=method%3DSitesManager.getSitesWithAtLeastViewAccess%26idSite%3Dn%2Fa&token_auth=..."
}

Test 3/3: SitesManager.getSitesIdFromSiteUrl

bool(false)

array(2) {
  [0]=>
  string(308) "HTTP/1.1 404 Not Found
Date: Wed, 14 Jun 2017 16:58:42 GMT
Server: Apache/2.4.25 (Unix) OpenSSL/1.1.0f mod_fcgid/2.3.9
Vary: accept-language,accept-charset
Upgrade: h2
Connection: Upgrade
Accept-Ranges: bytes
Transfer-Encoding: chunked
Content-Type: text/html; charset=utf-8
Content-Language: en

"
  [1]=>
  string(337) "https://www.home.zgaah.net:915/piwik/?module=API&method=API.getBulkRequest&format=json&urls[0]=method%3DAPI.getPiwikVersion%26idSite%3Dn%2Fa&urls[1]=method%3DSitesManager.getSitesWithAtLeastViewAccess%26idSite%3Dn%2Fa&urls[2]=method%3DSitesManager.getSitesIdFromSiteUrl%26idSite%3Dn%2Fa%26url%3Dhttps%3A%2F%2Fwww.zgaah.net&token_auth=..."
}