Configuration includes a Citrix Netscaler for internal and external access.  Netscaler services show everything is UP on the back-end server (only checks port 8888, which is what the server is configured to listen on.  It has worked in the past.

From external, the Captcha displays like a broken image, but internally, Captcha displays OK.  Tried different browsers (Chrome, IE, Edge) with same results.

Internal

External

Any ideas???