Java Proxy fails randomly with error 498 Invalid Token

[TranNgo]

We have set up a self hosted Java proxy according to the instructions: https://github.com/Esri/resource-proxy.  It fails randomly with a popup prompting for credentials often after a long period of inactivity. The code runs without errors locally. Any tips on how to debug?

<?xml version="1.0" encoding="utf-8" ?>

<ProxyConfig allowedReferers="*"

                logFile="proxy_log.log"

                logLevel="INFO"

                mustMatch="true">

    <serverUrls>

    <serverUrl url="https://aaa.com/gis1/rest/services/SABL"

                   matchAll="true"

                   username="domain\username"

                   password="password"

                   tokenServiceUri="https://aaa.com/gis1/tokens/"/> 

  </serverUrls>

</ProxyConfig>