Since installing 15.2.5, lots of "Your session may have timed out"

Had two more clients bring up the same problem today.  I was fortunate to have one of them this time open to having a phone call with me.  He was working from home, connected to work VPN.  I asked if he had a home machine he could try from.  He did.  Logged into the site no problem.  So he's going to contact their IT management tomorrow and get someone in touch with me.  Also asked him to try with his work machine at the end of his workday, after he disconnects from work VPN.

One client's IT team got involved today and resolved their problem getting to our site by SSL/Forward Bypassing our site on their proxy server.  I spoke, albeit briefly, with their IT analyst who was on the task.  Between the two of us, the only system change on either side that occurred in the time period when these connection attempts began to fail was our ServU MFT upgrade from 15.2.4 to 15.2.5.

I'll pose this to the next client IT team I have a chance to engage with and share anything I learn.

EDIT - since forum is not allowing me to post another reply:

Had another client yesterday that was able to add a bypass for our site on their proxy server, and were able to connect successfully again.  However, their security team will not allow a permanent bypass to be placed.  Instead, I asked if they can connect using SFTP - which we also listen for.

I believe this confirms now that something changed in 15.2.5 that is affecting connection from clients who use a proxy server.  At least some/most of them.  All these that I've been working with were connecting to us fine prior to our upgrade to 15.2.5

ivodlouhy This seems to be a common problem since 15.2.5 continues to exist in 15.3.

Please could this be looked into a fixed? I'm getting a increasing number of user reporting the same issue as well.

Thanks for letting know, checking it.

This seems be problem related to loadbalancer settings, I will give an update here once our solution investigation and testing complete.

Thanks ivodlouhy really appreciate you looking into this.

Thanks for investigation. Does "related to loadbalancer" mean, that this problem only exists with loadbalancer enabled in Serv-U? I have this problem without any loadbalancer.

I've seen this without the Serv-U load balancer, I think ivodlouhy may have been referring to external load balancers. For example, I have seen this when a user was behind a service like https://www.iboss.com/

We have identified this problem in configuration with either external loadbalancer or proxy.

In case of this problem please contact customer support they should be able to help based on our last investigation and solution we prepared.

Thanks. Will you release a Hotfix for this problem, too?

We will deliver final fix in next release. The date has not been agreed yet. Will give an update here once it is known.

We will deliver final fix in next release. The date has not been agreed yet. Will give an update here once it is known.