diff --git a/composer.json b/composer.json
index 6efbf21..429924c 100644
--- a/composer.json
+++ b/composer.json
@@ -13,16 +13,15 @@
     }
   ],
   "require": {
-    "php": ">=5.5.9",
-    "docusign/esign-client": "^3.0"
+    "php": "^7.2",
+    "docusign/esign-client": "^4.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "5.3.*"
+    "phpunit/phpunit": "8.2.*"
   },
   "autoload": {
     "psr-4": {
       "DocuSign\\Rest\\": "src/"
     }
-  },
-  "minimum-stability": "dev"
+  }
 }
diff --git a/src/Api/BaseApi.php b/src/Api/BaseApi.php
index 5e2e901..20e51df 100644
--- a/src/Api/BaseApi.php
+++ b/src/Api/BaseApi.php
@@ -38,12 +38,17 @@ abstract class BaseApi
     public function __construct(ApiClient $apiClient)
     {
         $this->apiClient = $apiClient;
+        $this->initClient();
+    }
+
+    private function initClient()
+    {
         $docusignClass = str_replace(__NAMESPACE__, "DocuSign\\eSign\\Api", get_class($this)) . 'Api';
-        $this->client = new $docusignClass($apiClient->getClient());
+        $this->client = new $docusignClass($this->apiClient->getClient());
     }
 
     /**
-     * Magic method to construct an options model or call an apimethod
+     * Magic method to construct an options model or call an api method
      * @param $method
      * @param $args
      * @return mixed
@@ -56,7 +61,12 @@ public function __call($method, $args)
         }
 
         if ($method !== 'login' && !$this->apiClient->isAuthenticated()) {
+            $host = $this->apiClient->getHost();
             $this->apiClient->authenticate();
+            // If the host has changed, update host on client config
+            if ($host !== $this->apiClient->getHost()) {
+                $this->initClient();
+            }
         }
 
         if ($this->usesAccountId) {
@@ -68,7 +78,7 @@ public function __call($method, $args)
 
     /**
      * Get an options object or all of them for current Api class
-     * 
+     *
      * @param null $method
      * @return array|mixed
      * @throws ClassNotFoundException
@@ -119,4 +129,4 @@ public function setOptionsObject($method, $args)
 
         return $optionClass;
     }
-}
\ No newline at end of file
+}
diff --git a/src/Client.php b/src/Client.php
index 690fff5..123cf2b 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -2,7 +2,7 @@
 
 namespace DocuSign\Rest;
 
-use DocuSign\eSign\ApiClient;
+use DocuSign\eSign\Client\ApiClient;
 use DocuSign\eSign\Configuration;
 
 
@@ -67,6 +67,11 @@ public function __construct($params = [])
             $this->{$key} = $val;
         }
 
+        $this->initApiClient();
+    }
+
+    private function initApiClient()
+    {
         $this->client = new ApiClient($this->setConfiguration());
     }
 
@@ -80,6 +85,11 @@ public function setConfiguration()
             ]));
     }
 
+    public function getHost()
+    {
+        return $this->host;
+    }
+
     /**
      * This magic method is to instantiate all classes in the \DocuSign\eSign\Model namespace
      *
@@ -123,7 +133,7 @@ public function __get($name)
         if (array_key_exists($name, $this->_api_container)) {
             return $this->_api_container[$name];
         }
-        
+
         if (!class_exists($apiClass = "DocuSign\\Rest\\Api\\" . ucfirst($name))) {
             throw new Exceptions\ClassNotFoundException("Cannot Find Api Class $apiClass");
         }
@@ -132,7 +142,7 @@ public function __get($name)
     }
 
     /**
-     * Authenticates api client and stores account_id
+     * Authenticates api client, stores account_id, and updates host if changed by docusign
      *
      * @return $this
      */
@@ -140,9 +150,17 @@ public function authenticate()
     {
         if (!isset($this->account_id)) {
             $accounts = $this->authentication->login();
-            $allAccounts = $accounts->getLoginAccounts();
-            $account = $allAccounts[0];
+            $login_accounts = $accounts->getLoginAccounts();
+            $account = $login_accounts[0];
             $this->account_id = $account->getAccountId();
+            $base_url = $account->getBaseUrl();
+            $base_url = strtolower(substr($base_url, 0, strpos($base_url,'/restapi') + 8));
+            // If the host has changed, update host on client config
+            if ($this->host !== $base_url) {
+              $this->host = $base_url;
+              $this->_api_container = [];
+              $this->initApiClient();
+            }
         }
 
         $this->authenticated = true;
@@ -177,4 +195,4 @@ public function getClient()
     {
         return $this->client;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/LoginTest.php b/tests/LoginTest.php
index 62b6964..c764467 100644
--- a/tests/LoginTest.php
+++ b/tests/LoginTest.php
@@ -1,6 +1,8 @@
 <?php
 
-class LoginTest extends PHPUnit_Framework_TestCase
+use PHPUnit\Framework\TestCase;
+
+class LoginTest extends TestCase
 {
 	public function testLogin()
 	{
@@ -17,4 +19,4 @@ public function testLogin()
 
 		$this->assertStringMatchesFormat('%d', $docusign->getAccountId());
 	}
-}
\ No newline at end of file
+}
diff --git a/tests/SignatureRequestTest.php b/tests/SignatureRequestTest.php
index 8cf3a42..7875009 100644
--- a/tests/SignatureRequestTest.php
+++ b/tests/SignatureRequestTest.php
@@ -1,6 +1,8 @@
 <?php
 
-class SignatureRequestTest extends PHPUnit_Framework_TestCase
+use PHPUnit\Framework\TestCase;
+
+class SignatureRequestTest extends TestCase
 {
 	public function testSignatureRequest()
 	{
@@ -48,4 +50,4 @@ public function testSignatureRequest()
 
 		$this->assertInstanceOf(\DocuSign\eSign\Model\EnvelopeSummary::class, $envelopeSummary);
 	}
-}
\ No newline at end of file
+}