Strange problem with Ruby script that was working until recently -- invalid app token?

We have a Ruby script that has been working fine until very recently.  We needed to rebuild the server that this script runs on, and after doing so, the server is now running Centos 7.4, 64 bit.  We have another, almost identical Centos 7.4 server that is also running almost this same script, and it runs fine there.  But on the server that we rebuilt, we cannot get this script to run any more. 

In the script, we use the Ruby QuickBase Client gem (quickbase_client (1.0.25)) to create the connection to QuickBase and run some queries.  However, now the script fails once we connect, and it returns the following error:

Error code: 24 text: Invalid Application Token: detail: An Application Token must be supplied.

We double-checked the app token that we are providing in the script, and it was correct.  Just in case, we tried creating a new app token for the database in question, and then tried that, but we got the same response.  

The code we use to create the connection is below (password and apptoken is masked out):

 qbc = QuickBase::Client.new(username = "quickbase_listupdates@taurigroup.com", password = "XXXXX", appname = "People", useSSL = true, printRequestsAndResponses = false, stopOnError = true, showTrace = false, org = "taurigroup", apptoken = "XXXXXXXX", debugHTTPConnection = false, domain = "quickbase", proxy_options = nil)

We are at a loss at this point as to why QuickBase is reporting that this is either a bad or missing app token.  Anyone have any suggestions or pointers? 

Thanks