diff --git a/data.php b/data.php
index 23c48b02..2b822018 100644
--- a/data.php
+++ b/data.php
@@ -3,10 +3,22 @@
     $setupVars = parse_ini_file("/etc/pihole/setupVars.conf");
 
     $hosts = file_exists("/etc/hosts") ? file("/etc/hosts") : array();
-    $log = new \SplFileObject('/var/log/pihole.log');
-    $gravity = new \SplFileObject('/etc/pihole/list.preEventHorizon');
-    $whitelist = new \SplFileObject('/etc/pihole/whitelist.txt');
-    $blacklist = new \SplFileObject('/etc/pihole/blacklist.txt');
+
+    // Check if pihole.log exists and is readable
+    $logListName = checkfile("/var/log/pihole.log");
+    $log = new \SplFileObject($logListName);
+
+    // Check if preEventHorizon exists and is readable
+    $gravityListName = checkfile("/etc/pihole/list.preEventHorizon");
+    $gravity = new \SplFileObject($gravityListName);
+
+    // whitelist.txt is optional and might not be there
+    $whiteListFile = checkfile("/etc/pihole/whitelist.txt");
+    $whitelist = new \SplFileObject($whiteListFile);
+
+    // blacklist.txt is optional and might not be there
+    $blackListFile = checkfile("/etc/pihole/blacklist.txt");
+    $blacklist = new \SplFileObject($blackListFile);
 
     /*******   Public Members ********/
     function getSummaryData() {
@@ -238,8 +250,9 @@
 
     /******** Private Members ********/
     function gravityCount() {
-        $preEventHorizon = exec("grep -c ^ /etc/pihole/list.preEventHorizon");
-        $blacklist = exec("grep -c ^ /etc/pihole/blacklist.txt");
+        global $gravityListName,$blackListFile;
+        $preEventHorizon = exec("grep -c ^ $gravityListName");
+        $blacklist = exec("grep -c ^ $blackListFile");
         return ($preEventHorizon + $blacklist);
     }
 
@@ -255,7 +268,8 @@
     }
 
     function countDnsQueries() {
-        return exec("grep -c \": query\\[\" /var/log/pihole.log");
+        global $logListName;
+        return exec("grep -c \": query\\[\" $logListName");
     }
 
     function getDnsQueriesAll(\SplFileObject $log) {
@@ -350,7 +364,8 @@
     }
 
     function countBlockedQueries() {
-        return exec("grep \"gravity.list\" /var/log/pihole.log | grep -c \" is \"");
+        global $logListName;
+        return exec("grep \"gravity.list\" $logListName | grep -c \" is \"");
     }
 
     function getForwards(\SplFileObject $log) {
diff --git a/php/auth.php b/php/auth.php
index 4d87d975..7972480b 100644
--- a/php/auth.php
+++ b/php/auth.php
@@ -15,9 +15,12 @@ function log_and_die($message) {
 }
 
 function check_cors() {
+    $setupVars = parse_ini_file("/etc/pihole/setupVars.conf");
+    $ipv4 = isset($setupVars["IPV4_ADDRESS"]) ? explode("/", $setupVars["IPV4_ADDRESS"])[0] : $_SERVER['SERVER_ADDR'];
+
     // Check CORS
     $AUTHORIZED_HOSTNAMES = array(
-        'http://' . $_SERVER['SERVER_ADDR'],
+        'http://' . $ipv4,
         'http://' . $_SERVER['SERVER_NAME'],
         'http://pi.hole',
         'http://localhost'
@@ -30,8 +33,16 @@ function check_cors() {
 
     // Since the Host header is easily manipulated, we can only check if it's wrong and can't use it
     // to validate that the client is authorized, only unauthorized.
-    if(isset($_SERVER['HTTP_HOST']) && !in_array("http://".$_SERVER['HTTP_HOST'], $AUTHORIZED_HOSTNAMES)) {
-        log_and_die("Failed Host Check: " . $_SERVER['HTTP_HOST'] .' vs '. join(', ', $AUTHORIZED_HOSTNAMES));
+    $server_host = $_SERVER['HTTP_HOST'];
+
+    // If HTTP_HOST contains a non-standard port (!= 80) we have to strip the port
+    if(strpos($server_host,":"))
+    {
+        $server_host = parse_url($_SERVER['HTTP_HOST'], PHP_URL_HOST);
+    }
+
+    if(isset($_SERVER['HTTP_HOST']) && !in_array("http://".$server_host, $AUTHORIZED_HOSTNAMES)) {
+        log_and_die("Failed Host Check: " . $server_host .' vs '. join(', ', $AUTHORIZED_HOSTNAMES));
     }
 
     if(isset($_SERVER['HTTP_ORIGIN'])) {
diff --git a/php/func.php b/php/func.php
index 060b4f43..37ef790f 100644
--- a/php/func.php
+++ b/php/func.php
@@ -7,4 +7,16 @@ function is_valid_domain_name($domain_name)
         preg_match("/^[^\.]{1,63}(\.[^\.]{1,63})*$/", $domain_name)); //length of each label
 }
 
-?>
\ No newline at end of file
+function checkfile($filename) {
+    if(is_readable($filename))
+    {
+        return $filename;
+    }
+    else
+    {
+        // substitute dummy file
+        return "/dev/null";
+    }
+}
+
+?>
diff --git a/php/get.php b/php/get.php
index eeae056c..fada75b9 100644
--- a/php/get.php
+++ b/php/get.php
@@ -7,7 +7,9 @@ $type = $_GET['list'];
 if($type !== "white" && $type !== "black")
     die("Invalid list parameter");
 
-$rawList = file_get_contents("/etc/pihole/${type}list.txt");
+require "func.php";
+
+$rawList = file_get_contents(checkfile("/etc/pihole/${type}list.txt"));
 $list = explode("\n", $rawList);
 
 // Get rid of empty lines
diff --git a/settings.php b/settings.php
index 87bfc815..2ae032ea 100644
--- a/settings.php
+++ b/settings.php
@@ -106,10 +106,17 @@
 	{
 		$DHCP = false;
 		// Try to guess initial settings
-		$DHCPdomain = explode(".",$piHoleIPv4);
-		$DHCPstart  = $DHCPdomain[0].".".$DHCPdomain[1].".".$DHCPdomain[2].".201";
-		$DHCPend    = $DHCPdomain[0].".".$DHCPdomain[1].".".$DHCPdomain[2].".251";
-		$DHCProuter = $DHCPdomain[0].".".$DHCPdomain[1].".".$DHCPdomain[2].".1";
+		if($piHoleIPv4 !== "unknown") {
+			$DHCPdomain = explode(".",$piHoleIPv4);
+			$DHCPstart  = $DHCPdomain[0].".".$DHCPdomain[1].".".$DHCPdomain[2].".201";
+			$DHCPend    = $DHCPdomain[0].".".$DHCPdomain[1].".".$DHCPdomain[2].".251";
+			$DHCProuter = $DHCPdomain[0].".".$DHCPdomain[1].".".$DHCPdomain[2].".1";
+		}
+		else {
+			$DHCPstart  = "";
+			$DHCPend    = "";
+			$DHCProuter = "";
+		}
 	}
 	if(isset($setupVars["PIHOLE_DOMAIN"])){
 		$piHoleDomain = $setupVars["PIHOLE_DOMAIN"];
@@ -361,7 +368,7 @@
 	{
 		$excludedDomains = explode(",", $setupVars["API_EXCLUDE_DOMAINS"]);
 	} else {
-		$excludedDomains = "";
+		$excludedDomains = [];
 	}
 
 	// Exluded clients in API Query Log call
@@ -369,7 +376,7 @@
 	{
 		$excludedClients = explode(",", $setupVars["API_EXCLUDE_CLIENTS"]);
 	} else {
-		$excludedClients = "";
+		$excludedClients = [];
 	}
 
 	// Exluded clients