If you have an RTL8125 (2.5GbE), the driver often negotiates down to 1Gbps only. True 2.5G requires a heavily patched driver that may not survive an ESXi patch update.
If you are unwilling to buy new hardware, consider abandoning VMware: esxi 8 realtek
This means . The few remaining developers have moved to Proxmox or other platforms. Do not expect an official Realtek driver for ESXi 8.0 Update 3 or any future ESXi 9 release. If you have an RTL8125 (2
Download the official VMware ESXi 8.0 ISO from Broadcom’s website (requires a free account). If you have an RTL8125 (2.5GbE)
(Realtek) driver, run these commands in a PowerShell 7 environment with PowerCLI installed: Add Depots: powershell Add-EsxSoftwareDepot .\VMware-ESXi-