Sensitivity of cable modem to nearby wiring?


Senior Member
New Spectrum internet. The installer ran the coax well clear of lights on the bottom of joists in the basement to the equipment cabinet but it was dangling in a few places. I put it up in the joists (I-joists with pre punched holes for wires) for what looked cleaner but it did cross a couple power wires - just crossed, not parallel. I may put it back where it was to see if that helps. I did one speed test with 55 mS of jitter which most would consider high - most tests are under 5 mS. It's the Spectrum modem so I can't see the signal levels.

Doesn't seem like the coax would be that sensitive to nearby wires. They put a tap box in to drop the signal 6 dB. Other than that I don't know the levels. They said something about download signals being good without the attenuation but upload was the need for adjustment.
Can you get to ? That's the default IP on Spectrum modems. Depending on the model, it's either available without authentication, or auth info may be found on a sticker somewhere on that modem (check bottom).
Just a thought. Make sure the cable isn't grounded in two places. Perhaps the cable is grounded and some router or ethernet cable is grounded at another location causing induction in the shield and noise in the conductor.
The connection eventually failed completely. Spectrum said it was down in the area but an unreported outage. It had been totally out for about half an hour at that point. Apparently they don't report all their outages - good way to keep the numbers looking better I guess - just lie about them. It's working fine this morning with low jitter. Can't access the modem - from what I read it just isn't possible.
Did you get a modem from Spectrum or a combination modem, router, switch wireless access point? What is the mfg and model number of what you got from them?
It is just the default modem they gave me when they installed. Labeled for Spectrum. E31U2V1. They also gave me a wifi router free for a year but $5 a month after that. Planning to turn that in as I would rather use my own.
It is a Hitron E31U2V1 modem. It does not have access to the IP or wireless.

Reviews on Amazon for the Hitron E31U2V1 ==>
2 star review:
Spectrum sent this modem to me as a mandatory upgrade to my personally-owned Motorola/Arris DOCSIS 3.0 modem. I figured I'd try it out since it just showed up on my doorstep. Big mistake. This modem is straight garbage. Upload speeds can't exceed 10Mbit even when connected directly to the modem. Most of the time I never see close to the download speeds I pay for. The first morning I had this modem, I joined a Teams meeting at work, and every participant complained that I was cutting out while speaking. My experience of that meeting was the same on my end: all participants cutting out.
I ended up ordering a Motorola 2.5Gbps DOCSIS 3.1 from Amazon to replace it.
Carrier pigeons would be better than this pile of junk.
1 star review:
This modem is a DOCSIS 3.1 and was sent to me by Spectrum back around late 2019 (as someone else mentioned it was supposed to be an upgrade) and for whatever reason it is way slower than a DOCSIS 3.0 modem I ended up buying myself (Arris SB6183). So now I just keep it as a backup modem in case my good modem dies. The difference in download speed is drastic. I tested it by downloading a file and I only get 3mb/s versus the Arris SB6183 which gives me 28mb/s download speed. I'm assuming it's a hardware issue because I tested 2 different routers (TP-LINK AC1700 and ASUS RT-AX58U) and both were faster with the Arris SB6183 I got. Spectrum needs to give out better routers.
You can buy a refurbished Arris Modem with 3.1 Docis on Ebay for less than $100 or a Docis 3.0 modem for less than $30.

I would turn it in and buy new or used Docis 3.1 modem. Even an Arris Docis 3.0 modem would work better for you.

Amazon has them all.

Your PFsense Firewall and Spectrum will work with any of the coaxial cable modems on Amazon.

Go baby steps here...first a new modem, then maybe a managed Gb switch then a managed Gb WAP.

Not all cable companies let you use your own modem.

Verizon FIOS connectivity was bridged such that I had two networks. One bridged to my own firewall and one for the Verizon FIOS STBs.

Most residential cable is asymmetrical such that they provide good speeds down but limit the uploading. Commercial cable typically is symmetrical. This issue came up for the last few years do to all of the folks using zoom on video conferencing calls.

I have been using Motorola and Arris modems since the beginning of Internet provided by cable companies. Think first use was with Jones Cable.

I am currently using an Arris SB6190 modem with XFinity. Works great. My run from the outside to the telco wall in the basement is about 15 feet direct connection with no splitters as I do not use TV. I did have to put an attenuator on my cable as the signal was too high for the Arris modem.

Any checking that the cable company does is only outside here at the dmark where the cable goes in to the house. They can tell what your signals look like with their tools. Typically though they blame issues on your infrastructure or modem. I have not had one modem fail me in the last 30 years now.

Here is the diagnostic web page:

Google optimal numbers for diagnostics for comparison. I tried the newer Arris SB8200 (90 days) and it was OK but looking now at the Motorola Gb modem.

The modem itself is a router so you do double NAT from the PFSense box.

Internet cable ==> modem ==> PFSense box.

The modem boots up first time in TFTP mode. It goes to a Spectrum server to get a configuration (Tier) based on what you are paying for using the MAC and or serial number of your modem. It then saves the configuration on the modem. You cannot read this configuration nor make any changes to it. That said it is all open source code.

My PFSense RTT (the lower the better) sits around 8-10 for IPv4 and IPv6. If you have Fiber it will sit around 1-2 ms. So you can diagnose your signal using the Arris web page below and your RTT on your PFSense box. I have a UPS that takes care of the modem, PFSense box and switches. That said if you have a local power failure your modem will stay up. If it is an area Spectrum outage it may not stay up depending how the transport from your home to the internet. Here with XFinity area outages my internet goes down even though the modem stays up.

Best speed testing is vial DSL Reports dot com, Toast dot al as it goes to different servers. Today / this morning I am seeing that the Internet is really slow and response times to the internet servers are in the double digit ms. Something is going on today here in the midwest with XFinity.

There are issues today via the Internet down detector....

and with it is more of an Internet than a service provider issue.

That said I have two VPN site to site tunnels going right now and 1 VPN to VPN service tunnel going and the outage is not affecting these tunnels. (house to house, house to bank, laptop to VPN server)

FireShot Capture 096 - Status -


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