Hi,

    I installed Jenkins version 2.375.1. After installing Jenkins and tried to login the login works and logs show Jenkins installed successfully.

The next page shows This Jenkins instance appears to be offline. When I checked the logs, get the below exception.

2022-12-21 17:49:20.332+0000 [id=41]    WARNING    hudson.model.UpdateCenter#updateDefaultSite: Upgrading Jenkins. Failed to update the default Update Site 'default'. Plugin upgrades may fail.
java.net.SocketTimeoutException: connect timed out
    at java.base/java.net.PlainSocketImpl.waitForConnect(Native Method)
    at java.base/java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:107)
    at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:412)
    at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:255)
    at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:237)
    at java.base/java.net.Socket.connect(Socket.java:608)
    at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:177)
    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:508)
    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:603)
    at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:276)
    at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:375)
    at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:396)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1253)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1187)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1081)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1015)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1592)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1520)
    at hudson.model.DownloadService.loadJSON(DownloadService.java:122)
    at hudson.model.UpdateSite.updateDirectlyNow(UpdateSite.java:219)
    at hudson.model.UpdateSite.updateDirectlyNow(UpdateSite.java:214)
    at hudson.model.UpdateCenter.updateDefaultSite(UpdateCenter.java:2672)
    at jenkins.install.SetupWizard.init(SetupWizard.java:209)
    at jenkins.install.InstallState$InitialSecuritySetup.initializeState(InstallState.java:182)
    at jenkins.model.Jenkins.setInstallState(Jenkins.java:1134)
    at jenkins.install.InstallUtil.proceedToNextStateFrom(InstallUtil.java:99)
    at jenkins.install.InstallState$Unknown.initializeState(InstallState.java:88)
    at jenkins.model.Jenkins$15.run(Jenkins.java:3500)
    at org.jvnet.hudson.reactor.TaskGraphBuilder$TaskImpl.run(TaskGraphBuilder.java:177)
    at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:305)
    at jenkins.model.Jenkins$5.runTask(Jenkins.java:1161)
    at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:221)
    at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:120)
    at jenkins.security.ImpersonatingExecutorService$1.run(ImpersonatingExecutorService.java:70)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:834)
2022-12-21 17:49:20.334+0000 [id=59]    INFO    hudson.util.Retrier#start: The attempt #1 to do the action check updates server failed with an allowed exception:
java.net.SocketTimeoutException: connect timed out
    at java.base/java.net.PlainSocketImpl.waitForConnect(Native Method)
    at java.base/java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:107)
    at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:412)
    at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:255)
    at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:237)
    at java.base/java.net.Socket.connect(Socket.java:608)
    at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:177)
    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:508)
    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:603)
    at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:276)
    at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:375)
    at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:396)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1253)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1187)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1081)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1015)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1592)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1520)
    at hudson.model.DownloadService.loadJSON(DownloadService.java:122)
    at hudson.model.UpdateSite.updateDirectlyNow(UpdateSite.java:219)
    at hudson.model.UpdateSite.updateDirectlyNow(UpdateSite.java:214)
    at hudson.PluginManager.checkUpdatesServer(PluginManager.java:2039)
    at hudson.util.Retrier.start(Retrier.java:62)
    at hudson.PluginManager.doCheckUpdatesServer(PluginManager.java:2010)
    at jenkins.DailyCheck.execute(DailyCheck.java:93)
    at hudson.model.AsyncPeriodicWork.lambda$doRun$0(AsyncPeriodicWork.java:102)
    at java.base/java.lang.Thread.run(Thread.java:834)

Note : Even though after changing the HTTPs to HTTP in hudson.model.UpdateCenter.xml it doesn't work