First off let me say I know this has been a frequent question posted here regarding slow upload speeds on the UTM. I have been a UTM user for well over a decade probably closer to 15 years. I may not be a Bob expert but I know my way around the software.
I recently got an ATT symmetric 1GB fiber line and plugged it up to my UTM VM. At first, performance was normal and expected. I was getting close enough to max throughput with the understanding that I would be getting less because it was running in a VM on older hardware. All fine. Then one day, and I honestly don't know when, upload performance just took a nose dive. I would get 3-5Mbps on uploads. Sometimes spiking to 7%.
I did all the normal things, turned off IDS, turned off web filtering, confirmed 1500 MTU on all NICs, you name it. I have a small Ubiquiti FW as a backup and it was able to get full 1Gb from all my VM's and my physical boxes, so I know my internal network is fine and can handle it. I even built not 1 but 2 brand new UTMs. One I did a restore of a config and another I did unconfigured, no settings. The performance of all these UTMs is the same 5Mbps upload. Download speeds are fine and close to theoretical maximums. I am at a complete loss. I do NOT want to migrate my services to Ubiquiti. I want to keep using the UTM. What else can I do? there are no IDS or filtering logs to check since all of that is disabled. Is this an ATT thing? Is there some special setting I need to make on the ATT FW or UTM interface setting I need to make to get this to work? It doesn't have to be perfect, but symmetrical upload is all I want.
Tell more about the specs of your system.
What CPU does it have? Amount of RAM?
Are you using Intel NICs or Realtek?
Would QoS cause these problems?
Can someone here say if using IPv4 or IPv6 would make a difference?
It's hard to tell if it's a hardware issue since you are running the UTM in a VM (instead of bare metal) which will create overhead and reduce performance.
The ESXi hosts are Dell R720 servers with Broadcom and Intel physical NICS. The procs are Xeon 2.6GHz 8 cores 2 sockets. The VM NICS are VMXNET3.
I checked QoS as well on the initial existing UTMs and it was not configured. Same on the new ones I built.
Ooooo IPV6. I hadn't thought of that.
I agree about the virtualization overhead not being the best for performance. I am getting anywhere from 500-900Mbps on download. If I can get the same on upload, I would be ok.