Our company recently upgraded from Citrix version 6 (server 2008 R2 host servers) to 7.15 (Server 2016 host servers). We have an application that we host where external users connect with a WYSE terminal and serial connections (antiquated, yes...however it has to interface with certain equipment). On our Citrix 6 platform, we were able to use regular ICA connections and these were stable. When we upgraded, we weren't able to use ICAs anymore so we did this by configuring a broker server on the WYSE (with a url like "https://apps.myorganization.com/Citrix/Ourapps/PNAgent/config.xml").

The connection initially works, and will be stable for a fair amount of time. However we have noticed that the serial traffic is interrupted at least once a day. The serial seems to stop responding altogether once this happens, and we have to stop the app and restart it so that a new Citrix session opens. We have noticed that when connecting this way, even our old farm does this with the exception of one server. So far we have been unable to determine what specific setting may be allowing this old server to remain up and neither has Citrix. They most frequently occur every night within the same timeframe, 12 AM to 6 AM, however there have been a few, sporadic occurrences at other times. If we are using the PNAgent URL as shown above, would this use our NetScaler, and would load balancing possibly be causing the issue? If not, what other settings could be causing this?

Also, forgive my Citrix ignorance in advance...I actually the person that wrote this application and offer basic support, and am not typically involved in Citrix support.

  • 1
    I have never played with serial connections within citrix, but some thoughts: a) why did you not update to an LTSR version (ver. 7 1912 LTSR) b) whether a netscaler is used or not, depends on your configuration and network layout c) load balancing is most likely not the issue here. Load balancing occurs only that multiple sessions are distributed evenly within the available servers, but not within one session... one active session always stays on the same server.
    – Martin
    Feb 2, 2021 at 13:47
  • ignore point a), I just noticed that 1912 does not support windows server 2008 - and that 7.15 is an LTSR release.
    – Martin
    Feb 2, 2021 at 13:57

1 Answer 1


So in the end, this had nothing to do with serial connections. When our new Citrix VDA servers were configured, they were configured to use DHCP. This shouldn't theoretically have been such a huge issue, as the DHCP lease times were set to be a long time out. However, for some unknown reason, the DHCP release was happening daily. When DHCP released and renewed the IP, it briefly took down any of the connections to those servers. Our solution was to set the servers to use static IPs, as Citrix recommended to use these settings anyway.

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