Post kernel 6.8.12-8, bug was introduced which causes the NIC to crash and not recover. Revert to 6.8.12-8 kernel to prevent the problem. Other temporary solutions include turning off cpu-offloading options. In the Node console:
apt updateapt install proxmox-kernel-6.8.12-8-pveproxmox-boot-tool kernel pin 6.8.12-8-pve