Nov 15 2021
21 Comments (21 New)

Good morning, I went though a lot of reviews looking for a solution but I didn’t find anything related to this issue so I decided to contact you guys and ask for help.


I’ve been using this app (Microsoft Remote Desktop) on my Ipad for a long time, but now that I got a new Ipad (software version 14.8.1 ) I am getting this error: “Unable to connect, Error code 0x204”


This issue happens only when I am connected via VPN using T-Mobile network. When using VPN on a WiFi network it works perfectly, it also works fine when used via WiFi within the same network where my computer is connected here in my office.

(I also tried on my Iphone and same situation, same error message under the same conditions, it doesn’t work on T-Mobile network via VPN )


The bad (or good)  thing is that everything works perfectly on my “old Ipad” no issues at all, it works everywhere on any of those conditions mentioned above, the software version of my old Ipad is 12.5.5


Any ideas on how to make it work on my new Ipad Air 4th Generation?


Thanks in advance.



Status changed to: Active


We will investigate this issue and keep you updated.



Status changed to: Tell us more


There shouldn't be anything specific to the RD client running on your old iPad's software vs your new iPad's software that would affect error code 0x204. Is this error reproducible? Or has it just happened a couple times?

Copper Contributor

Good morning, thanks for your prompt reply and yes, it is happening all the time, I mean, RD Client on T-Mobile is not working at all on any of the 5 new Ipads we just purchase for some executives. I have to insist: RD works perfectly when I am connected to WiFi within our network and also when using VPN on an external WiFi network but it doesn't work when there is no Wifi just the T-Mobile data network, which is when is most needed. The VPN connects fine but when RD is open the error shows.

The "old" Ipad works fine all the time in all scenarios described below. I have both here with me we can test at any moment.


Hi @Ale_rod1500 ,

The app engineering team does not have any guidance to provide related to your Remote Desktop issue at the time as it seems mostly related to accessing session hosts via VPN using T-Mobile network which is not an issue they have seen/delt with before.

Have you filed a support request for this issue yet? Hands-on debugging with our customer support team sounds like the next best step.


Furthermore, have you looked at Remote Desktop clients FAQ | Microsoft Docs. Specifically there is a section on "VPN doesn't work" which includes:


VPN issues can have several causes. The first step is to verify that the VPN works on the same network as your PC or Mac computer. If you can't test with a PC or Mac, you can try to access a company intranet web page with your device's browser.

Other things to check:

  • The 3G network blocks or corrupts VPN. There are several 3G providers in the world who seem to block or corrupt 3G traffic. Verify VPN connectivity works correctly for over a minute.
  • L2TP or PPTP VPNs. If you are using L2TP or PPTP in your VPN, please set Send All Traffic to ON in the VPN configuration.
  • VPN is misconfigured. A misconfigured VPN server can be the reason why the VPN connections never worked or stopped working after some time. Ensure testing with the iOS device's web browser or a PC or Mac on the same network if this happens.

How can I test if VPN is working properly?

Verify that VPN is enabled on your device. You can test your VPN connection by going to a webpage on your internal network or using a web service which is only available via the VPN.

How do I configure L2TP or PPTP VPN connections?

If you are using L2TP or PPTP in your VPN, make sure to set Send all traffic to ON in the VPN configuration.

Copper Contributor

Good morning, thanks for your follow up and research, we found out that there is an issue with the latest version between IOS and VPN connectivity, with previous versions everything works perfectly, but with the most recent it doesn't work, we were able to make it work using domain name server instead of IP addresses which is weird because it should be able to work with both, we still are also researching on our side. Happy Holidays.

Status changed to: Closed

Sounds good, closing the issue for now. Happy holidays @Ale_rod1500 

Copper Contributor

I'm having a very similar issue.  Was the above issue ever resolved? 


I'm trying to use Microsoft's Remote Desktop Client to connect to my Windows 10 PC via an OpenVpn connection from 2 different devices:  my Android phone and my iPhone 12 mini.


The Android version of the remote desktop client and the IOS version of the remote desktop client both work perfectly when using WiFi connections (from another network).


However, only the Android client can successfully connect with WiFi turned off (via its T-Mobile cellular connection). 


Turning WiFi off on the iPhone 12 mini returns Error code: 0x204 when I try to connect using T-Mobile's connection. 


As workarounds I've tried various permutations of using IP address, pc name, DDNS, user names, email address, but nothing works.


I'm trying to avoid opening any ports in my router.


P.S. I am getting the same exact behaviors on a second Windows 10 machine.


P.P.S.  I tried another experiment, this time using the iPhone 12 mini with only the (T-Mobile) cellular enabled as a hotspot connection for my WiFi Samsung tablet.  The Remote Desktop client on my Samsung Tablet was able to connect via OpenVPN to my Windows 10 PC (through T-Mobile using the iPhone 12 mini's hotspot).


My theory is the ios Remote Desktop client app is the culprit. 


Any thoughts?





Copper Contributor

Hi All,


I am experiencing this issue with the latest iPad, OpenVPN connects effortlessly, Remote Desktop clocks and then gives the error 0x204. As with the others, when using WiFi in the office it works as well.


Others in the organisation with iPhones and iPads continue to have effortless access to the Remote Desktop

Copper Contributor

We finally were able to make it work using Domain Name Server instead of IP addresses when creating and setup the VPN connections. Give it a try.

Copper Contributor

Resolved, thank you so much.


Hi @Ale_rod1500 ,

When you mention using a DNS, what do you mean in particular? i.e. setting up a DNS on a home network or registering with a dynamic DNS server.


Copper Contributor

Just as a "FYI":  I'm not sure how the "DNS server workaround" mentioned above was implemented.  As another test, for "PC Name" in the RD Client, I replaced the private IP address of the Windows PC I am trying to connect to with my dynamic DNS server address but as I expected, I still could not connect via OpenVPN.  The reason I doubted it would work is that my dynamic DNS server address points to the internet address of my router (the same router that serves as my OpenVPN server) and not to the target PC with the private IP address.  As before, as soon as I switch from cellular to WiFi the connection works fine.

Copper Contributor

On my Macbook Pro, Tunnelblick was the issue, as soon as I moved to OpenVPN, the issue was resolved.


In relation to my iPhone, I set up another remote desktop with exactly the same settings and it worked perfectly.


I think if OpenVPN works, it maybe worth checking the Log File and see what it is connecting to.


Good luck

Copper Contributor

I used to setup the RDC to be established based on IP Addresses ( but since it didn't work I tried by name. IE. jwindsor-dt and it works fine.

Copper Contributor



I'm assuming the name you are referring to is the name Windows displays by clicking Settings > System > Remote Desktop (with the text appearing):

"Use this PC name to connect from your device: yourhostname"


I'm wondering if this workaround is successful because for your situation, use of the pc's hostname causes circumvention of the VPN connection altogether.  If I'm right, you are instead connecting via another mechanism (such as SMB).  In any event, hostname doesn't work for me when I connect via cell phone using OpenVPN from either Android or iPhone.  For the Android Remote Desktop app the host's private IP address does work.  For the iPhone Remote Desktop app, it doesn't.


Copper Contributor

not exactly, I have to go back to where the problem started: on  my new Ipad the RDC app didn't work when connected VPN using T-Mobile network to access my PC , after some research I noticed that the fix was to add my PC to the RDC App using the PC host name (instead of IP), the pc name found in Windows - Control Panel - System - <System Name> and with this modification the connection started to work when VPN using T-Mobile from anywhere. 

Copper Contributor

I have the same issue but am able to connect with RDP using the Jump Desktop iOS app, so it appears to be an issue with the Microsoft Remote Desktop Mobile app.


Copper Contributor

I am having a similar issue.  I have tested iPad connected to my verizon hotspot, iphone as a hotspot, and two other backup cellular connections.  If I connect to verizon, or either of the two backups (all 3 of these have IP addresses that start with 192.168.1.....) and then connect to my company's VPN the RDClient app gives me the Error code: 0x204.  However, when I connect my iPad to my iPhone hotspot (ip 172.20.1......) and the VPN, it connects.  I mention the IPs because the desktops i'm attempting to connect to are also on a subnet that starts with 192.168.1.....  My Network Admin thought that may be playing a part of the issue.  In addition I tested these same 4 wifi connections with my windows laptop using the native RDP and all combinations worked.  
Its the iPad with RDClient & wifi in 192.168.1 subnet that cause the error.  I tried my host name instead of ip, but that did not work.
Thank you

Copper Contributor

As I mentioned before, our issue using the RD Client on Ipad accessing servers or computers via VPN was fixed as soon as we started using Hostnames instead of IP Addresses.

I.E:  PCname.domain.com.


Copper Contributor

Thank you Ale_rod1500,

Unfortunately using hostnames did not work for my VPN.  

Copper Contributor

TLDR: I added a 2nd VPN server to my private network and when using that server there is no problem. In my view this tends to shift the blame away from the Microsoft Remote Desktop APP and towards the VPN server itself (but that is debatable).


I wanted to circle back and provide new information regarding the problem I have experienced using Microsoft’s Remote Desktop iPhone App when accessing my network via a VPN over a T-Mobile wireless connection in light of some new testing results.

Specifically: when using Microsoft Remote Desktop App version 10.4.5 (5227) on my iPhone and a T-Mobile wireless connection with a VPN connection into my home network:


Microsoft Remote Desktop fails returning Error code: 0x204 using ‘VPN Server A’ but connects properly with ‘VPN Server B’ (see below).


Interestingly, if I instead use my Pixel 4a (5G)’s Microsoft Remote Desktop version and a T-Mobile wireless connection and make a VPN connection into my home network:


Microsoft Remote Desktop connects properly using either VPN server.


VPN Server A: ASUS RT-AC68U Router’s (Firmware built-in OpenVPN Server


VPN Server B: OpenVPN server version 2.5.5 x86_64-pc-linux-gnu running on a Windows 10 Hyper-V hosted Ubuntu 22.04 LTS Virtual Machine.


This second VPN server works perfectly well although I'm required to this Windows 10 computer (and the virtual Ubuntu machine) powered on to insure availability of my private network via Remote Desktop.  At some point I'll check with the folks at ASUS and see if they are willing to work on this issue (assuming they can reproduce it).