Oracle Confidential Such low transfer rates are usually an indication of lots of retransmissions, primarily caused by some offloading issue (TCP segmentation or checksum). Try to disable TCP segmentation offloading in the guest with "sudo ethtool -K <interface_name> tso off". If it does not help, try to disable other types of offloading.
Regards, Aleksey Oracle Confidential ________________________________ From: vbox-dev <[email protected]> on behalf of fabian via vbox-dev <[email protected]> Sent: Monday, 3 August 2026 8:02 AM To: [email protected] <[email protected]> Subject: [vbox-dev] SLOW FILE TRANSFERS More as an FYI as I continue testing and research, but I've found that certain NICs are slow when data is transferred off the VM. So far, I've only found it when using a bridged adapter and crossing a router. For example, VM has 82540EM, IP 192.168.25.208, sftp to the Host on 192.168.10.176. Transfer from the host is as expected, but transferring the file back to the host is really slow (see attached pics). I also tested the reverse, SFTP server on VM, and perform the transfer on the host. Same issue, transferring data to the VM was fast, data leaving the VM was slow. Rich Fabian
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