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excessive wireless dropoffs with Dell tablets and VPN-based hosted application

Hello all,

I have a doctor’s office that has several wireless tablets and laptops, they’re all Dell’s based on the doctor’s individual preferences. Most are XT3 tablets.

We have a hosted application on the cloud with a VPN connection to the hosted data center using Comcast Internet and Cisco ASA devices. Prior to Comcast we had AT&T DSL. I only mention this, as we’ve had problems with both Internet providers on our end.

The problem is the doctors get booted off of the Remote Desktop session several times a day. Note again they are all wireless. Any of the offices hardwired machines do not get the session drop at the same time.

On one of the more common devices, I have done all the updates for the system -  bios, wireless adapter, video, even sata drive firmware,  etc. none of this has helped.

Since the hardwired desktops do not drop I have been focusing on the wireless is the issue. I have tried two different wireless access points, both on the higher end, both I’ve used before with great success. When I walked the office with the tablet I consistently have between 4 to 5 bars, which means 80 to 100%, no matter where I’m at.

I’m starting to suspect it is an issue with the VPN and wireless devices, whether it be timing, packet size, etc. related.

Any help or a direction would be greatly appreciated.

Happy holidays
Avatar of gt2847c
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Does the hosted app require the VPN be client based rather than a site to site?  IPSec VPNs do not recover well from dropped packets, so either switching to a site to site connection or an SSL VPN may help connectivity issues.
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It is a site to site VPN, I should've said that when I mentioned the Cisco ASA's.

No software VPN client involved at all.
Avatar of Rob Williams
I would never use wireless for a mission critical application, random disconnects are why most accounting apps will not support wireless networks and specify this in their system requirements.  

A VPN exaggerates the dropped connection where a straight RDP connection should automatically reconnect and most users may not notice.  If it is server 2008 or newer you could use the TS Gateway service and connect securely using SSL and RDP with no need for VPN.

With a VPN over wireless you have dual encryption services and two services that can fail.
Are the access points all on the same channel?  Also keep in mind that they might be getting the disconnect when their device is switching from one access point to another. How big is the office abd how many access points? Are the access points all the same models? Also, what type of encrytion are you using?
Having 4 or 5 bars does not mean it is because of your network.  I think you'll find it is just the cumulative signal strength of all the networks on that frequency.  I would use something like WirelessNetView to see how many other networks are in your area.
To answer a few of the posted questions:

1) I totally agree wireless is not the best solution for a production network. Wireless in doctor's offices is more and more prevalent with the change in healthcare. As Doctors move towards electronic records management systems, they are carrying wireless devices into exam rooms, writing prescriptions and orders on the spot.  

2) We are using wpa2 encryption.

3) There is only one access point in the office. It is located in the center of the office and the exam rooms are all within 30 feet of the AP.
My point about wireless not being an ideal solution in a production environment was not related to security, though that is an issue, but rather wireless has a tendency to have minor disconnects due to surrounding EMI or other reasons, especially when the device is moving room to room.  With strait SSL-RDP this is not that significant an issue but with VPN's it is much more common, and with greater interruptions, though less so with site-to site VPN's than VPN clients.

I assume with medical records, replacing the VPN with RDP and SSL (TS Gateway)  is not an option.
I suggested checking for other networks because if there are other doctor's offices next door, they will be doing the same thing with their networks and can be interfering with yours.
Dave, an excellent suggestion. Oh yeah, there are many WL networks in the surrounding businesses. I will check into that and also changing channels ?
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Dave Baldwin
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Dave, you really got me in the right direction. I used the Nirsoft application and discovered about 13 wireless networks in the building and at least 5 or 6 on the same channel, 11. No one was using channel 8 so I changed to channel 8.

But also found what we think to be the real source of the issues: I have only been there once, this last Friday, when I saw the dropoffs. And when it happened I saw one of the docs walking down the hallway with a portable phone. yes, they have two of them I did not know about. And yes, they are 2.4 GHz. We are replacing them :-) Unbelievable that I did not catch that before now !
Glad to help, thanks for the points.  WiFi was originally intended to be a low speed app for cash registers in stores.  Now it and the frequency band are being used for way too many things.