Solved! Losing my mind -- cannot figure out significantly slower speeds on my desktop

[JM Aggie08]

I've reached the depth of my networking knowledge. For whatever reason, I'm regularly only getting 10% of the network speed I should be getting on my home network, specifically on my Desktop. Mine and wife's phones are pulling about ~400mbps over wifi which we'd expect, but the damn desktop (connected via LAN) is hitting 80-90mbps on Ookla and Google's speedtests. I've run both the Device (desktop to interweb) and Gateway (AT&T Gateway to AT&T), of which the Device test came back 80-90mbps and the Gateway test 800-950mbps. My network from the desktop is as follows:

Desktop -> Netgear managed switch (plug n play, no VLANs or anything custom) -> Asus Router (nothing custom) -> AT&T Gateway -> Interweb

Couple things to note:

• I had a small unmanaged netgear switch prior to the managed switch -- thought this was the issue, removed it, had short-term normal speeds, but then back to slow
• I recently added in the Asus Router, using passthrough from the AT&T Gateway
• Disabled all firewall settings on AT&T gateway, being managed by Asus Router now
• I initially thought this resolved the issue, as I was hitting 900mbps+ on my desktop, but hours later, it was back to 80-90mbps consistently
• Once slow again, did a ip release/renew, cleared DNS cache, reset winsock -- appeared to fix issue, but went back to slow speeds again
• Tried the above resets once more, and it remained slow -- no short-term improvement this time
• No third-party antivirus, VPN, proxy, etc -- already checked inet setting on the desktop
• Rebooting the AT&T gateway seems to have intermittently brought normal speeds back, but not consistently, and they return back to slow shortly after
• I've tried using a USB 3.0 -> gigabit ethernet, and got the same slow speeds

This is the ONLY device this is happening on. If it was consistently terrible I'd understand. But at random, specifically after doing something, network speeds are improved.

Looking for any thoughts ya'll might have. Please let me know if you need any additional information.

 

[VirtualLarry]

Sounds like the connection is spotty, and it's downgrading to a 100Mbit/sec connection.

What happens if you go into the NIC properties in windows, and force a Link Rate of 1000Mbit/sec FD?

Chances are, this is an issue with a damaged or degraded cable. Is it run through the wall?

Edit: Could also be an issue with the port on the router or switch, or even your NIC or Windows driver for the NIC.

 

[JM Aggie08]

Sounds like the connection is spotty, and it's downgrading to a 100Mbit/sec connection.

What happens if you go into the NIC properties in windows, and force a Link Rate of 1000Mbit/sec FD?

Chances are, this is an issue with a damaged or degraded cable. Is it run through the wall?

Edit: Could also be an issue with the port on the router or switch, or even your NIC or Windows driver for the NIC.

Crazy, man -- opened up the properties, saw link speed was 100/100. Opened it up in devmgmt, and Speed & Duplex was set to auto-negotiated -- theoretically, it should have been pulling 1000/1000 with that. Set it to 2.5Gbps and it's back to normal -- link speed is 1000/1000, speed tests are coming back normal.

What would cause that to auto-negotiate down to 100/100 like that? Potential driver issue? Would have thought it was getting that instruction from the switch. Like I said, it was just this specific machine having issues.

In any case -- THANK YOU.

 

[VirtualLarry]

You didn't tell me that it was a 2.5Gbit/sec NIC.

I had the same problem. Mostly, since I switched to PCI-E RealTek 2.5Gbit/sec NIC, rather than trying to utilize a USB one (also RealTek), *AND* replaced my cable to the switch, the problem seems to have gone away.

There may be driver issues with those as well. I found that the default Microsoft drivers were more stable, connection-wise, than the specific RealTek drivers.

One other question, does it still have that issue while browsing or streaming, while booted into a live Linux USB distro. That might indicate that a cable replacement might be necessary.

Edit: Can also be NIC / switch slight incompatibilities.

Edit: Even if you get the link rate issue corrected, consider that my Ryzen R5 3600 6C/12T CPU and 32GB of 3600 DDR4, only speedtests @ 300Mbit/sec on a gigabit line (when I had gigabit), when under a 100% CPU load. When CPU was not fully loaded, I could hit 940Mbit/sec.

 

[JM Aggie08]

You didn't tell me that it was a 2.5Gbit/sec NIC.

I had the same problem. Mostly, since I switched to PCI-E RealTek 2.5Gbit/sec NIC, rather than trying to utilize a USB one (also RealTek), *AND* replaced my cable to the switch, the problem seems to have gone away.

There may be driver issues with those as well. I found that the default Microsoft drivers were more stable, connection-wise, than the specific RealTek drivers.

One other question, does it still have that issue while browsing or streaming, while booted into a live Linux USB distro. That might indicate that a cable replacement might be necessary.

Edit: Can also be NIC / switch slight incompatibilities.

Edit: Even if you get the link rate issue corrected, consider that my Ryzen R5 3600 6C/12T CPU and 32GB of 3600 DDR4, only speedtests @ 300Mbit/sec on a gigabit line (when I had gigabit), when under a 100% CPU load. When CPU was not fully loaded, I could hit 940Mbit/sec.

Honestly didn't consider it being 2.5gig as a factor. That's interesting though. I might screw with drivers a bit too. The odd thing is that this is only a recent development. I've not had issues since building the PC in January. Suspect it could have been a recent RealTek update. So strange.

 

[JM Aggie08]

Spoke too soon! Was back to 100/100 even with the Speed/Duplex being forced.

Ordered a new keystone for the wall, going to test/replace the other ends along the way. I missed the patch panel in my network flow -- just another point to test, and no issues with other devices.

 

[Justinus]

While I also think it could be a cable/physical connection issue my symptoms were different - full throughout on gigabit but my internet would disconnect frequently for a few seconds each time. Can you run a patch cable straight from the machine to the router to eliminate the in-wall cabling entirely for testing?