I have a very strange issue with PFsense as router running in KVM with CentOS 7. https connections are incredibly slow (10KB/s or less), and uploads over https simply don't work; for example using https://imgur.com over https loads, but uploading an image will take minutes, after which it says it failed.
I have a dual-wan setup with a 192.168.178.x/24 subnet between the PFsense VM and the 2 ADSL router/modems. The router/modem's NAT functionality can not be turned off, so I've simply put them in the same subnet and connected them to eachother with only 1 DHCP server active, the first router sitting on .1 and the second on .2. The PFsense box sits on .5. The private network behind pfsense is 172.16.x.x/16. The PFsense virtual machine runs on a CentOS 7 KVM hypervisor with 2 intel Gbe NICs, bridged using a linux bridge with the VM network cards, using virtIO drivers, if it makes any difference.
I do have a Squidproxy, however it is not enabled for https connections, and https accesses do not appear in Squid's logs, and turning off or removing Squid does not make a difference. Moving myself into the 192.168.178.x/24 subnet before PFsense DOES make a difference however, as suddenly everything runs smoothly again, and any https content loads instantly.
Does anyone have a clue what could be going on? Anything I could try to diagnose? I've tried wireshark and aside for the slowness I don't see anything unusual.. Any suggestions are welcome!
edit: I'm currently running memtest86+ inside a VM (those shouldn't give errors either right?), and I have 1 error so far, although it seems to be outside the range of memory I've granted the VM so I'm a bit confused.. I will update once I have more info. Might run a full memtest on the host later if I can clear users off the host for a moment.