FYI I did open a support case 630538. They are researching how to increase this length.
In the mean time I may have found my own fix. This page is poorly designed for large node or interface counts.
This is what I believe is happening:
Page loads each node and all available interfaces
User selects an element to add in and hits submit
The whole table appears to be sent back to the server, including all checked and unchecked elements
If you have a ton of nodes or interfaces then this process gets slower and slower. Also you have to upload more data back to the server. It seems that IIS / Asp has a default value for the web request length for data sent from the user to the server.
Reviewing similar issues at links such as:
http://www.easyalgo.com/knowledgebase/system.web.httpexception-maximum-request-length-exceeded.aspx
It took some time but I found the web.config file which affects the VQNM in the folder: C:\inetpub\SolarWinds\Orion\Voip\web.config
I added this to the config - in the section <system.web>:
<httpRuntime executionTimeout="3600" maxRequestLength="16384" />
This allows the webpage to complete without directing me to an error message. I am still waiting on Support to review to see if they suggest this method or provide an alternate. I am also not sure this is actually adding them into the Infrastructure. I don't get errors on the webpage then again the tested nodes are not showing. I am still learning how VQNM is expected to function.