RT-AX86U slow download speeds

[GW4C]

I've had this router for a little over two years and it has functioned perfectly until this last month. I have 2gig symmetrical fiber internet and when using the router's built in speed test, I was getting ~1,800mbps download and ~2,000mbps upload until mid-March. For the past couple of weeks, the speed test is showing ~400mbps download and ~2,000mbps upload. I have no idea why the download speeds are so slow. A technician from the internet provider stopped by and confirmed that the ONT is flashing a green light which means that the receiving client (my router) is sub gig. They connect the ONT to two different routers they brought with them and both of them were showing ~2,000mbps download speeds. So it has to be the router. Does anyone have suggestions on what I can do to troubleshoot this issue?

Some additional details:

• The ONT is connected via Cat5E cable to the router's 2.5gb wan port.
• The router firmware version is 3.0.0.4.388_24231
• I have tried rebooting the router and ONT.
• I have not tried to factory reset the router.

[Saltgrass]

@jzchen   To early to tell .  The city freaked out because 911 was unusable during the transition.  It seems Spectrum gave no one any guidance as to their process.

[Saltgrass]

Oh, and one more thing, the image seems to show you have 52 devices connected.  Could it be the speed to your computer is being restricted due to those other devices?  

[GW4C]

I considered that also. Most of those devices are smart plugs and cameras that don't normally take up any bandwidth. Do you think that just having that many devices on one router could be affecting download speeds, even if they are not really using any bandwidth? 

[Saltgrass]

I wish I could say for sure, but they do have some load and perhaps the router keeps some in reserve for each one, just in case.

[GW4C]

Definitely possible. What's also odd is that on occasion, the download speeds will normalize and I'll get 2 gig download from all speedtest destinations. And this is with all devices connected. My ISP said that it could be a Pon issue.

[jzchen]

Just thought of this (duh, palm to the face).

At 2xx Mbps download you should be able to confirm this on any wired device connected to the router, by running speedtest.net or speedtest.net app?  2xx is much less than 1 Gig Ethernet...

@Saltgrass I like to set up household phones to use WiFi calling, which requires you to enter an E911 address.  Helpful if actual 911 is down, and if cell signal is poor.

[Saltgrass]

When you setup your new router, did you create a new network so the IoT devices would not get involved?

I don't suppose your configuration allows for plugging the Ethernet directly into your one computer, for testing?

I am not familiar with a Passive Optical Network.

If I had a 2 Gbps fiber connection, I am pretty sure I would be running Cat 6a Ethernet cable, just to make sure there were no bottlenecks.

[GW4C]

I used the same SSID for the new router. Didn't even think of testing the router without the LoT devices connected to it. And the ONT does allow for direct connections to the ethernet port of a computer. I tried it once last week with my laptop that has a 1 gig port and it had the same issue. Reduced download speeds and advertised upload speeds. : / 

[GW4C]

I had a tech come from the ISP's corporate office and spend about two hours with me diagnosing every aspect of my connection. He was very kind and walked me thought everything he was doing. In the end, we ruled out everything BUT the router. The ONT is fine. My cat5e wall patch is fine. The RT-AX86U for whatever reason is just not giving me 2gig download speeds. It seems to vary wildly by the hour. This occurred on my current 86U and the new 86U Pro router I bought to test my connection. It must be something wrong with the router itself or perhaps the current firmware. I'm really curious if anyone else with this router gets consistent 2 gig download speeds. I might make another post asking the community. 

[jzchen]

Was he able to get 2 Gigs into the computer directly?  That test shifted me towards their fault...