Can I set the RADIUS Client IP list to more than 20 entries?

While the UI in the configuration tool only shows 20 slots, the system will support more IPs/secrets in the client IP allow list.  You can edit the config.xml file found in the c:\programdata\surepassid\ folder to add more clients.

Make a backup copy of the file first, to be safe, then  add more client blocks in this section of the config.xml:

<?xml version="1.0" encoding="utf-8"?>
<appSettings xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Authserver>
    <Remote>
      <LoginName>redacted</LoginName>
      <LoginPW>redacted</LoginPW>
      <EndPoint>https://mfa.surepassid.com/</EndPoint>
      <Binding>WSHttpBinding_ISurePassAuthServerWCFService</Binding>
    </Remote>
  </Authserver>
  <radius>
    <Enable>TRUE</Enable>
    <Trace>TRUE</Trace>
    <AllowSingleFactor>FALSE</AllowSingleFactor>
    <Port>1812</Port>
    <RadProxyIP>127.0.0.1</RadProxyIP>
    <RadProxySecret>redacted</RadProxySecret>
    <RadProxyPort>1812</RadProxyPort>
    <ClientList>
      <Client>
        <SS>secret</SS>
        <IP>127.0.0.1</IP>
      </Client>
      <Client>
        <SS>secret</SS>
        <IP>192.168.0.87</IP>
      </Client>
      <Client>
        <SS>secret</SS>
        <IP>172.174.39.119</IP>
      </Client>
      <Client>
        <SS>secret</SS>
        <IP>192.168.56.1</IP>
      </Client>
      <Client>
        <SS>secret</SS>
        <IP>192.168.237.1</IP>
      </Client>
    </ClientList>