Solved Down speed capped ~100mbps (GT-AC2900)

[Tech9]

Hitron E31N2V1

This modem has Ethernet port lights. Green - Fast Ethernet. Amber - Gigabit Ethernet.

 

[drinkingbird]

This modem has Ethernet port lights. Green - Fast Ethernet. Amber - Gigabit Ethernet.

Nice of them to make it opposite every other device out there.

 

[hoodles]

This modem has Ethernet port lights. Green - Fast Ethernet. Amber - Gigabit Ethernet.

Port is amber

Router WAN static IP 10.0.0.1 255.255.255.0 (don't worry about DNS or gateway)
Laptop wired LAN static IP 10.0.0.2 255.255.255.0 (don't worry about DNS or gateway)
Laptop into airplane mode or disable wifi
iperf -s on laptop
iperf client to 10.0.0.2 on your phone.

While you're at it see what physical link speed the laptop and router are reporting. Both should be 1000. Would be nice to confirm duplex but you have to run a powershell command in windows and go into the CLI on the router to see that. Unlikely that it would be negotiating to 1000/Half (and that wouldn't explain the 93 megs either unless it was one heck of a coincidence).

If it exceeds 100, have ruled out the router as the issue
if it is limited to under 100 still, we know to focus on the router.

If it exceeds 100 my best guess is some strange negotiation issue between asus and the modem.

Not impressive speeds, but definitely above 100M:

Accepted connection from 10.0.0.1, port 38890
[  5] local 10.0.0.2 port 5201 connected to 10.0.0.1 port 39056
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-1.00   sec  26.1 MBytes   219 Mbits/sec
[  5]   1.00-2.00   sec  26.2 MBytes   220 Mbits/sec
[  5]   2.00-3.00   sec  23.8 MBytes   200 Mbits/sec
[  5]   3.00-4.00   sec  23.9 MBytes   200 Mbits/sec
[  5]   4.00-5.00   sec  22.7 MBytes   191 Mbits/sec
[  5]   5.00-5.02   sec   372 KBytes   142 Mbits/sec

Both laptop and router reported 1Gbps. Which I guess means that if you're out of ideas I need to try to explain this to a Spectrum tech. I'm getting anxious already...

 

[drinkingbird]

Port is amber



Not impressive speeds, but definitely above 100M:

Accepted connection from 10.0.0.1, port 38890
[  5] local 10.0.0.2 port 5201 connected to 10.0.0.1 port 39056
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-1.00   sec  26.1 MBytes   219 Mbits/sec
[  5]   1.00-2.00   sec  26.2 MBytes   220 Mbits/sec
[  5]   2.00-3.00   sec  23.8 MBytes   200 Mbits/sec
[  5]   3.00-4.00   sec  23.9 MBytes   200 Mbits/sec
[  5]   4.00-5.00   sec  22.7 MBytes   191 Mbits/sec
[  5]   5.00-5.02   sec   372 KBytes   142 Mbits/sec

Both laptop and router reported 1Gbps. Which I guess means that if you're out of ideas I need to try to explain this to a Spectrum tech. I'm getting anxious already...

I wonder if their documentation is backwards, on most devices green is gig and amber is 100M. Was it also amber when you tested with your laptop directly plugged in (when you got over 100M)?

Your phone or wifi is probably limiting the speeds above to less than impressive (you got similar on your LAN) so no issue there, it has confirmed the router is capable of over 100M end to end.

You don't have anything special for ISP settings, like PPPoE etc?

Just to rule out possible MTU issue, when all is back to normal and router is in the path, from your laptop try:
ping -f -l 1472 google.com
make sure that succeeds (which would confirm your WAN MTU is 1500, the default setting of the Asus).

Other than that, yeah, I'm out of ideas, strange issue indeed. It does seem to imply something is negotiating at 100M but if both ports are showing 1000......

 

[hoodles]

I wonder if their documentation is backwards, on most devices green is gig and amber is 100M. Was it also amber when you tested with your laptop directly plugged in (when you got over 100M)?

Your phone or wifi is probably limiting the speeds above to less than impressive (you got similar on your LAN) so no issue there, it has confirmed the router is capable of over 100M end to end.

You don't have anything special for ISP settings, like PPPoE etc?

Just to rule out possible MTU issue, when all is back to normal and router is in the path, from your laptop try:
ping -f -l 1472 google.com
make sure that succeeds (which would confirm your WAN MTU is 1500, the default setting of the Asus).

Other than that, yeah, I'm out of ideas, strange issue indeed. It does seem to imply something is negotiating at 100M but if both ports are showing 1000......

Yes both amber, I just tried again to confirm.

And then strangest thing happened....after I set everything back to normal and went to grab my old DOCSIS 3.0 I ran another speedtest. Full speeds. I literally made no changes and have no idea what happened. I think the Spectrum modem, scared it was about to be replaced by an old Surfboard, started cooperating. Though I'm open to more rational speculation

Absolutely insane, but I'm not going to look a gift horse in the mouth. Especially when it comes to the arcane mystical rites of network setups.

@drinkingbird @Tech9 Thank you for taking the time to troubleshoot with me. This is a wonderful forum with extremely helpful people.

 

[Tech9]

I wonder if their documentation is backwards

No, normal for Hitron products.

Absolutely insane

Monitor it because other Hitron products in the past had firmware bug causing stuck LAN ports at 100Mbps with amber Gigabit port light.

 

[Datalink]

That was a very long time ago, fixed with a firmware update at the time. I haven't seen that come up on any of the modems since that time.

 

[drinkingbird]

That was a very long time ago, fixed with a firmware update at the time. I haven't seen that come up on any of the modems since that time.

Maybe an old modem that finally updated its firmware. Stuck at 100M is the only logical explanation at this point, though the Asus should have been showing 100 also. Perhaps it is intermittent and OP just was looking in the GUI at the right time but testing at the wrong. Odd. I'd say if it comes back get the modem swapped out and just tell them sometimes it comes up at 100 and other times 1000, don't mention anything about a router (or say it has the same behavior when directly connected to PC).