diff --git a/apps/user_ldap/js/wizard/view.js b/apps/user_ldap/js/wizard/view.js
index 1a89eba35156f..30a00d614ccef 100644
--- a/apps/user_ldap/js/wizard/view.js
+++ b/apps/user_ldap/js/wizard/view.js
@@ -86,7 +86,8 @@ OCA = OCA || {};
 			var agent = view.configModel.configuration.ldap_dn;
 			var pwd   = view.configModel.configuration.ldap_agent_password;
 
-			if((host && port  && base) && ((!agent && !pwd) || (agent && pwd))) {
+			if(((host && port && base) || (host && base && host.indexOf('ldapi://') > -1 ))
+        && ((!agent && !pwd) || (agent && pwd))) {
 				view.enableTabs();
 			} else {
 				view.disableTabs();
@@ -107,7 +108,8 @@ OCA = OCA || {};
 			var userFilter  = this.configModel.configuration.ldap_userlist_filter;
 			var loginFilter = this.configModel.configuration.ldap_login_filter;
 
-			if(host && port && base && userFilter && loginFilter) {
+			if((host && port && base && userFilter && loginFilter) ||
+        (host && base && host.indexOf('ldapi://') > -1 && userFilter && loginFilter)) {
 				this.configModel.requestConfigurationTest();
 			} else {
 				this._updateStatusIndicator(this.STATUS_INCOMPLETE);
diff --git a/apps/user_ldap/lib/Wizard.php b/apps/user_ldap/lib/Wizard.php
index eb0b775345bd8..82d940ae453b1 100644
--- a/apps/user_ldap/lib/Wizard.php
+++ b/apps/user_ldap/lib/Wizard.php
@@ -20,6 +20,7 @@
  * @author Tobias Perschon <tobias@perschon.at>
  * @author Victor Dubiniuk <dubiniuk@owncloud.com>
  * @author Xuanwo <xuanwo@yunify.com>
+ * @author Vincent Van Houtte <vvh@aplusv.be>
  *
  * @license AGPL-3.0
  *
@@ -95,7 +96,10 @@ public function __destruct() {
 	 * @throws \Exception
 	 */
 	public function countEntries(string $filter, string $type): int {
-		$reqs = ['ldapHost', 'ldapPort', 'ldapBase'];
+		$reqs = ['ldapHost', 'ldapBase'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
 		if ($type === 'users') {
 			$reqs[] = 'ldapUserFilter';
 		}
@@ -201,11 +205,11 @@ public function countInBaseDN() {
 	 * @return int|bool
 	 */
 	public function countUsersWithAttribute($attr, $existsCheck = false) {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-			'ldapUserFilter',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase', 'ldapUserFilter'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return  false;
 		}
 
@@ -226,11 +230,11 @@ public function countUsersWithAttribute($attr, $existsCheck = false) {
 	 * @throws \Exception
 	 */
 	public function detectUserDisplayNameAttribute() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-			'ldapUserFilter',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase', 'ldapUserFilter'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return  false;
 		}
 
@@ -268,11 +272,11 @@ public function detectUserDisplayNameAttribute() {
 	 * @return WizardResult|bool
 	 */
 	public function detectEmailAttribute() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-			'ldapUserFilter',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase', 'ldapUserFilter'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return  false;
 		}
 
@@ -315,11 +319,11 @@ public function detectEmailAttribute() {
 	 * @throws \Exception
 	 */
 	public function determineAttributes() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-			'ldapUserFilter',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase', 'ldapUserFilter'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return  false;
 		}
 
@@ -344,11 +348,11 @@ public function determineAttributes() {
 	 * @throws \Exception
 	 */
 	private function getUserAttributes() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-			'ldapUserFilter',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase', 'ldapUserFilter'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return  false;
 		}
 		$cr = $this->getConnection();
@@ -400,10 +404,11 @@ public function determineGroupsForUsers() {
 	 * @throws \Exception
 	 */
 	private function determineGroups($dbKey, $confKey, $testMemberOf = true) {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return  false;
 		}
 		$cr = $this->getConnection();
@@ -480,10 +485,11 @@ public function fetchGroups($dbKey, $confKey) {
 	}
 
 	public function determineGroupMemberAssoc() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapGroupFilter',
-		])) {
+		$reqs = ['ldapHost', 'ldapGroupFilter'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return  false;
 		}
 		$attribute = $this->detectGroupMemberAssoc();
@@ -502,10 +508,11 @@ public function determineGroupMemberAssoc() {
 	 * @throws \Exception
 	 */
 	public function determineGroupObjectClasses() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return  false;
 		}
 		$cr = $this->getConnection();
@@ -529,10 +536,11 @@ public function determineGroupObjectClasses() {
 	 * @throws \Exception
 	 */
 	public function determineUserObjectClasses() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return  false;
 		}
 		$cr = $this->getConnection();
@@ -559,10 +567,11 @@ public function determineUserObjectClasses() {
 	 * @throws \Exception
 	 */
 	public function getGroupFilter() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return false;
 		}
 		//make sure the use display name is set
@@ -583,10 +592,11 @@ public function getGroupFilter() {
 	 * @throws \Exception
 	 */
 	public function getUserListFilter() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return false;
 		}
 		//make sure the use display name is set
@@ -609,11 +619,11 @@ public function getUserListFilter() {
 	 * @throws \Exception
 	 */
 	public function getUserLoginFilter() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-			'ldapUserFilter',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase', 'ldapUserFilter'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return false;
 		}
 
@@ -632,11 +642,11 @@ public function getUserLoginFilter() {
 	 * @throws \Exception
 	 */
 	public function testLoginName($loginName) {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-			'ldapBase',
-			'ldapLoginFilter',
-		])) {
+		$reqs = ['ldapHost', 'ldapBase', 'ldapUserFilter'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return false;
 		}
 
@@ -719,9 +729,11 @@ public function guessPortAndTLS() {
 	 * @return WizardResult|false WizardResult on success, false otherwise
 	 */
 	public function guessBaseDN() {
-		if (!$this->checkRequirements(['ldapHost',
-			'ldapPort',
-		])) {
+		$reqs = ['ldapHost'];
+		if(substr($this->configuration->ldapHost, 0, strlen('ldapi://')) != 'ldapi://') {
+			$reqs[] = 'ldapPort';
+		}
+		if (!$this->checkRequirements($reqs)) {
 			return false;
 		}
 
@@ -1318,6 +1330,8 @@ private function getConnection() {
 	 * @return array
 	 */
 	private function getDefaultLdapPortSettings() {
+		// LDAPI unix socket support: why are ports 7389 and 389 duplicated here?
+		// LDAPI unix socket support: why are tls values wrong here?
 		static $settings = [
 			['port' => 7636, 'tls' => false],
 			['port' => 636, 'tls' => false],
@@ -1349,6 +1363,8 @@ private function getPortSettingsToTry() {
 				$portSettings[] = ['port' => $port, 'tls' => true];
 			}
 			$portSettings[] = ['port' => $port, 'tls' => false];
+		} elseif ($port === 0) {
+			$portSettings[] = ['port' => '', 'tls' => false];
 		}
 
 		//default ports