After you add a new SharePoint web front end server to a SharePoint farm with an existing Extradium deployment, you must manually configure the web.config file present in the C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\WebServices\SecurityToken folder on this new server.
The following <membership> section must replace the one found by default:
<membership>
<providers>
<add name="ext" type="RioLinx.Extradium.Providers.ExtradiumMembershipProvider, RioLinx.Extradium.Providers, Version=3.0.0.0, Culture=neutral, PublicKeyToken=ee2f606d34db8cb1" />
</providers>
</membership>
<roleManager enabled="true">
<providers>
<add name="extg" type="RioLinx.Extradium.Providers.ExtradiumRoleProvider, RioLinx.Extradium.Providers, Version=3.0.0.0, Culture=neutral, PublicKeyToken=ee2f606d34db8cb1" />
</providers>
</roleManager>