Problem with backup configuration from WLC 9800-L

[szybkispec]

I have a problem with backup configruation from WLC 9800-L via TFTP. I get this message "Error in Configuring Backup & Restore Error opening file connection timed out " when I set backup. I have set up automatic backup (archive) on switches in this network and they perform without any problems and only WLC can't do it. I checked logs on WLC and I can't see any logs from this operation.

Could you have any idea where is the problem ? 

[Arshad Safrulla]

You can use the same archive configuration as your switches in the 9800 WLC as both new Cisco switches and WLCs are running IOS-XE. Once configured you can check the history by "show archive" command.

[szybkispec]

The same situation.  Messages:

:error - Timed out 

Although i write the same configuration like on switches.

[Arshad Safrulla]

Can you post your archive configuration?

I would also like to suggest that you add "ip tftp source-interface vlan/GE XXX" depending on the interface that has reachability to the TFTP server. I assume that you have added exceptions on the end device firewall where TFTP server is running and also in any network firewalls that are in the path.

[Rich R]

Even defining the source interface may not be enough - 9800 will follow the routing table.

So "show ip route 10.0.100.46" and see which way the WLC will route to the TFTP server (you may need to add a static route out of the correct interface).  Or maybe the TFTP server is only reachable through the Service Port (Gig0) interface which is in a separate VRF "Mgmt-intf"?  In that case "ip tftp source-interface gigabitEthernet 0" will put it in the right VRF and there's only one way out of there as long as you have a default route out of G0 configured in the Mgmt-intf VRF.
Note that general support for using the SP only started in 17.6.1 and it doesn't mention TFTP (although it might work anyway):
https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/17-6/config-guide/b_wl_17_6_cg/m_config-wmi.html
What version of IOS-XE is the WLC running?

[Scott Fella]

While you are having issues with tftp, why not use http and that will allow you to download the config manually then you can move it to the tftp server.  You can also click on save configuration button and then click on diff and download the running or startup, then once downloaded to your machine, you can move it anywhere you want.

[szybkispec]

I have observed that only files more ~20mb were losted, small files are send.

[JPavonM]

Then this is a problem with your TFTP server. I've seen this before and only using tftpd64 (Windows) solved the issue. I've not seen such problem using Linux boxes.

[Rich R]

20M is very big for a config file!
You can use packet capture to confirm why it's timing out (which end stops responding) but agree with @JPavonM that it's almost certainly your server.
Time to upgrade your server or use a different protocol?