Try polling five, run the custom polling code on every version below lollipop,...

Try polling five, run the custom polling code on every version below lollipop, only retry when the error number was EINTR (interrupt - this is handled by the system itself above lollipop.)

app/src/main/java/com/frostnerd/dnschanger/util/dnsproxy/DNSTCPProxy.java

@@ -174,7 +174,7 @@ public class DNSTCPProxy extends DNSProxy{
                     pollingFd.fd = ParcelFileDescriptor.fromSocket(socket).getFileDescriptor();
                     pollingFd.events = (short)OsConstants.POLLIN;
                 }
-                poll(polls, 3000);
+                poll(polls, 5000);
             }
             if(blockFd.revents != 0){
                 shouldRun = false;
@@ -199,14 +199,14 @@ public class DNSTCPProxy extends DNSProxy{
 
     private int pollTries = 0;
     private void poll(StructPollfd[] polls, int timeout) throws ErrnoException {
-        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && Build.VERSION.SDK_INT < Build.VERSION_CODES.M){
+        if(Build.VERSION.SDK_INT < Build.VERSION_CODES.M){
             pollTries++;
             try{
                 Os.poll(polls, timeout/pollTries);
                 pollTries = 0;
             } catch(ErrnoException ex){
                 LogFactory.writeMessage(vpnService, LOG_TAG, "Polling failed with exception: " + ex.getMessage() + "(Cause: " + ex.getCause() + ")");
-                if(pollTries < 3) poll(polls, timeout);
+                if(ex.errno == OsConstants.EINTR && pollTries <= 5) poll(polls, timeout);
                 else throw ex;
             }
         }else {

app/src/main/java/com/frostnerd/dnschanger/util/dnsproxy/DNSUDPProxy.java

@@ -166,7 +166,7 @@ public class DNSUDPProxy extends DNSProxy{
                     pollingFd.fd = ParcelFileDescriptor.fromDatagramSocket(socket).getFileDescriptor();
                     pollingFd.events = (short)OsConstants.POLLIN;
                 }
-                poll(polls, 3000);
+                poll(polls, 5000);
             }
             if(blockFd.revents != 0){
                 shouldRun = false;
@@ -191,14 +191,14 @@ public class DNSUDPProxy extends DNSProxy{
 
     private int pollTries = 0;
     private void poll(StructPollfd[] polls, int timeout) throws ErrnoException {
-        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && Build.VERSION.SDK_INT < Build.VERSION_CODES.M){
+        if(Build.VERSION.SDK_INT < Build.VERSION_CODES.M){
             pollTries++;
             try{
                 Os.poll(polls, timeout/pollTries);
                 pollTries = 0;
             } catch(ErrnoException ex){
                 LogFactory.writeMessage(vpnService, LOG_TAG, "Polling failed with exception: " + ex.getMessage() + "(Cause: " + ex.getCause() + ")");
-                if(pollTries < 3) poll(polls, timeout);
+                if(ex.errno == OsConstants.EINTR && pollTries <= 5) poll(polls, timeout);
                 else throw ex;
             }
         }else {