Error message while installing Kibana : Unable to connect to Elasticsearch. Error: Request Timeout after 30000ms

I have trouble installing Kibana. Elasticsearch have been installed without problem but when I tried with Kibana I get the following error message log [22:27:13.834] [warning][savedobjects-service] Unable to connect to Elasticsearch. Error: Request Timeout after 30000ms. Can someone help me?

Kibana can't connect to elasticsearch, it could be your config or your network. From the kibana host, try the standard curl test to elasticsearch. If that works, it's your KIbana config, if it fails, follow that path.

the installation of Kibana has stopped before completing so I don't have access to kibana host. I get this error message while trying to install kibana

This is kibana logs I get when I try to install it:

E:\ELKStack\kibana-7.9.2-windows-x86_64\kibana-7.9.2-windows-x86_64\bin>kibana
  log   [04:40:54.674] [warning][plugins-discovery] Expect plugin "id" in camelCase, but found: beats_management
  log   [04:40:54.686] [warning][plugins-discovery] Expect plugin "id" in camelCase, but found: triggers_actions_ui
[BABEL] Note: The code generator has deoptimised the styling of E:\ELKStack\kibana-7.9.2-windows-x86_64\kibana-7.9.2-windows-x86_64\x-pack\plugins\canvas\server\templates\pitch_presentation.js as it exceeds the max of 500KB.
  log   [04:41:46.884] [info][plugins-service] Plugin "visTypeXy" is disabled.
  log   [04:41:46.885] [info][plugins-service] Plugin "auditTrail" is disabled.
  log   [04:41:47.793] [warning][legacy-service] Some installed third party plugin(s) [xpack_main, monitoring, spaces, security, beats_management, apm_oss, console_legacy, elasticsearch, kibana, status_page, timelion] are using the legacy plugin format and will no longer work in a future Kibana release. Please refer to https://ela.st/kibana-breaking-changes-8-0 for a list of breaking changes and https://ela.st/kibana-platform-migration for documentation on how to migrate legacy plugins.
  log   [04:41:47.812] [warning][config][deprecation] Config key [monitoring.cluster_alerts.email_notifications.email_address] will be required for email notifications to work in 8.0."
  log   [04:41:47.886] [info][plugins-system] Setting up [92] plugins: [taskManager,licensing,observability,globalSearch,globalSearchProviders,code,usageCollection,ossTelemetry,telemetryCollectionManager,telemetry,telemetryCollectionXpack,kibanaUsageCollection,newsfeed,mapsLegacy,kibanaLegacy,translations,timelion,share,legacyExport,esUiShared,charts,bfetch,expressions,data,home,cloud,apmOss,console,consoleExtensions,searchprofiler,painlessLab,grokdebugger,management,upgradeAssistant,licenseManagement,watcher,indexPatternManagement,advancedSettings,fileUpload,dataEnhanced,savedObjects,visualizations,visTypeVislib,visTypeVega,visTypeTimeseries,visTypeTimelion,features,security,snapshotRestore,reporting,encryptedSavedObjects,ingestManager,indexManagement,rollup,remoteClusters,crossClusterReplication,indexLifecycleManagement,enterpriseSearch,beats_management,transform,ingestPipelines,maps,graph,canvas,visTypeTagcloud,visTypeTable,visTypeMetric,visTypeMarkdown,visualize,tileMap,regionMap,inputControlVis,discover,discoverEnhanced,dashboard,lens,dashboardMode,savedObjectsManagement,spaces,lists,eventLog,actions,case,alerts,alertingBuiltins,ml,securitySolution,infra,monitoring,logstash,apm,uptime]
  log   [04:41:48.109] [warning][config][plugins][security] Generating a random key for xpack.security.encryptionKey. To prevent sessions from being invalidated on restart, please set xpack.security.encryptionKey in kibana.yml
  log   [04:41:48.110] [warning][config][plugins][security] Session cookies will be transmitted over insecure connections. This is not recommended.
  log   [04:41:48.149] [warning][config][plugins][reporting] Generating a random key for xpack.reporting.encryptionKey. To prevent sessions from being invalidated on restart, please set xpack.reporting.encryptionKey in kibana.yml
  log   [04:41:48.151] [warning][config][encryptedSavedObjects][plugins] Generating a random key for xpack.encryptedSavedObjects.encryptionKey. To be able to decrypt encrypted saved objects attributes after restart, please set xpack.encryptedSavedObjects.encryptionKey in kibana.yml
  log   [04:41:48.153] [info][config][plugins][reporting] Chromium sandbox provides an additional layer of protection, and is supported for Win32 OS. Automatically enabling Chromium sandbox.
  log   [04:41:48.162] [warning][ingestManager][plugins] Fleet APIs are disabled due to the Encrypted Saved Objects plugin using an ephemeral encryption key. Please set xpack.encryptedSavedObjects.encryptionKey in kibana.yml.
  log   [04:41:48.237] [warning][actions][actions][plugins] APIs are disabled due to the Encrypted Saved Objects plugin using an ephemeral encryption key. Please set xpack.encryptedSavedObjects.encryptionKey in kibana.yml.
  log   [04:41:48.262] [warning][alerting][alerts][plugins][plugins] APIs are disabled due to the Encrypted Saved Objects plugin using an ephemeral encryption key. Please set xpack.encryptedSavedObjects.encryptionKey in kibana.yml.
  log   [04:41:48.371] [info][monitoring][monitoring][plugins] config sourced from: production cluster
  log   [04:41:48.605] [info][savedobjects-service] Waiting until all Elasticsearch nodes are compatible with Kibana before starting saved objects migrations...
  log   [04:41:48.607] [info][savedobjects-service] Starting saved objects migrations
  log   [04:41:48.629] [info][savedobjects-service] Creating index .kibana_task_manager_1.
  log   [04:41:48.632] [info][savedobjects-service] Creating index .kibana_1.
  log   [04:42:18.633] [warning][savedobjects-service] Unable to connect to Elasticsearch. Error: Request Timeout after 30000ms

just an update. I changed the proxy configuration and it worked.