Microsoft Exchange 2013 iApp - Can't login to OWA or ECP if more than one server is active in pool

[PS] C:\Windows\system32>Get-OwaVirtualDirectory -Server Server1 | fl

RunspaceId : 84554014-511f-4af3-869b-462f2e41fc6e DirectFileAccessOnPublicComputersEnabled : True DirectFileAccessOnPrivateComputersEnabled : True WebReadyDocumentViewingOnPublicComputersEnabled : True WebReadyDocumentViewingOnPrivateComputersEnabled : True ForceWebReadyDocumentViewingFirstOnPublicComputers : False ForceWebReadyDocumentViewingFirstOnPrivateComputers : False WacViewingOnPublicComputersEnabled : True WacViewingOnPrivateComputersEnabled : True ForceWacViewingFirstOnPublicComputers : False ForceWacViewingFirstOnPrivateComputers : False RemoteDocumentsActionForUnknownServers : Block ActionForUnknownFileAndMIMETypes : Allow WebReadyFileTypes : {.xlsx, .pptx, .docx, .xls, .rtf, .ppt, .pps, .pdf, .dot, .doc} WebReadyMimeTypes : {application/vnd.openxmlformats-officedocument.presentationml.pre sentation, application/vnd.openxmlformats-officedocument.wordproc essingml.document, application/vnd.openxmlformats-officedocument. spreadsheetml.sheet, application/vnd.ms-powerpoint, application/x-mspowerpoint, application/vnd.ms-excel, application/x-msexcel, application/msword, application/pdf} WebReadyDocumentViewingForAllSupportedTypes : True WebReadyDocumentViewingSupportedMimeTypes : {application/msword, application/vnd.ms-excel, application/x-msexcel, application/vnd.ms-powerpoint, application/x-mspowerpoint, application/pdf, application/vnd.open xmlformats-officedocument.wordprocessingml.document, application/ vnd.openxmlformats-officedocument.spreadsheetml.sheet, applicatio n/vnd.openxmlformats-officedocument.presentationml.presentation} WebReadyDocumentViewingSupportedFileTypes : {.doc, .dot, .rtf, .xls, .ppt, .pps, .pdf, .docx, .xlsx, .pptx} AllowedFileTypes : {.rpmsg, .xlsx, .xlsm, .xlsb, .vstx, .vstm, .vssx, .vssm, .vsdx, .vsdm, .tiff, .pptx, .pptm, .ppsx, .ppsm, .docx...} AllowedMimeTypes : {image/jpeg, image/png, image/gif, image/bmp} ForceSaveFileTypes : {.html, .swf, .spl, .htm, .dir, .dcr} ForceSaveMimeTypes : {Application/x-shockwave-flash, Application/octet-stream, Application/futuresplash, Application/x-director, text/html} BlockedFileTypes : {.vsmacros, .msh2xml, .msh1xml, .ps2xml, .ps1xml, .mshxml, .gadget, .mhtml, .psc2, .psc1, .msh2, .msh1, .aspx, .xml, .wsh, .wsf...} BlockedMimeTypes : {application/x-javascript, application/javascript, application/msaccess, x-internet-signup, text/javascript, application/xml, application/prg, application/hta, text/scriplet, text/xml} RemoteDocumentsAllowedServers : {} RemoteDocumentsBlockedServers : {} RemoteDocumentsInternalDomainSuffixList : {} FolderPathname : Url : {}