Intermittently high latency on WAN

[dum258]

Recently, I've been having intermittent lag when accessing the internet. After doing some investigating, I discovered that the latency on my WAN is very high (400ms+) and sporadic. I have attempted the following fixes:

• Rebooted ESXI, PfSense, and my modem
• Updated PfSense to the latest release (2.4.4-RELEASE-p3)
• Disabled Gateway monitoring & action (as the sporadic jumps in my WAN simply resets my GW)
• Implemented QOS (CoDel) @80% of the DL & UL speeds as per my internet package (just in case BufferBloat was the cause)
• Contacted my ISP and had a tech come out. He replaced the modem.

Unfortunately, none of these fixes solved my issue. Any advice?

Background info:

• Pfsense is running on ESXI (ver 6.7) on an R710 with Broadcom NICs (NetXtreme II 5709)
• Assigned 1 vCpu & 2 GB Ram. CPU and mem usage are around 10%
• Networking setup is Modem > PfSense WAN > PfSense LAN > Switch > devices
• My current setup has been running for over a year with no issues

1 week of WAN monitoring

1 month of WAN monitoring

Any help would be greatly appreciated.