Slow WAN speed after random period on WAN on intel Dual NIC

[hellrazo]

HI all...

Got this dual lan card
em1@pci0:2:0:1: class=0x020000 rev=0x06 hdr=0x00 vendor=0x8086 device=0x105e subvendor=0x8086 subdevice=0x135e
    vendor     = 'Intel Corporation'
    device     = '82571EB/82571GB Gigabit Ethernet Controller D0/D1 (copper applications)'
    class      = network
    subclass   = ethernet

Its running through proxmox with a partial passthrough

It works well for a while, but after 24 hours or a couple of days, my 500MB connection drops to below 100mbps

I never had this issue on PFsense for several years with this model of card so thats why I dare to ask here.
The modem is not limiting anything, i tested with another NIC on another system.


The setup is:
This 2x1gbe card using only one port for WAN / other port is unused (the behavior is observed on both ports )
Another card at 2x10gbe using only one port for wan, the other port is for the proxmox upstream itself.

Any clue before I try to change for another model (is there a compatibility issue)

thanks for any input