This issue occurs if Advanced State Power Management (ASPM) is activated at the BIOS / EFI of the server and the adapter used is unable to support ASPM.
Some network adapters based on the Intel 82599 10 Gigabit Ethernet Controller do not support ASPM, for example:
Intel Ethernet Converged Network Adapter X520-SR1
Intel Ethernet Converged Network Adapter X520-SR2
Intel Ethernet Converged Network Adapter X520-LR2
Intel Ethernet Converged Network Adapter X520-DA1
Intel Ethernet Converged Network Adapter X520-DA2
Note: This is not a complete list. There may be other PCIe adapters that do not support ASPM.
Resolution
To resolve or avoid network connectivity issues, disable ASPM on the BIOS / EFI configuration of the server. When ASPM is disabled, PCIe adapters without ASPM support operate normally.