Looking for new cable modem

Rich McCabe · January 2020

I recently replaced my modem with a Arris SB6190. I have been unable to use port 23 for telnet since. Arris is zero help and Mediacom says they are not blocking Port 23 and to talk to Arris.

My Motorola modem worked OK but I could not get it to work in bridge mode so as unable to connect my Ubiquity Firewall/router to it.

So back to the drawing board as being able to Telnet on 23 is important for a ham

Suggestions appreciated for ham use. I personally would rather it be basic as I have the routing and firewall covered.

This is a Mediacom cable 100MB cable connection.

Rich
kd0zv

David Decoons, wo2x · January 2020

Hi Rich

First off use a cable modem fully supported by your cable provider.

even though some modems you purchase 3rd party will work the cable company will not support firmware, etc.

i use an Arris TM1602G which my cable company supports for voice and data. I get full 300 MBps download.

Last, make sure your local router has port 23 opened to the private IP of the device on the network you want to telnet to.

dave wo2x

Rich McCabe · January 2020

Hey Dave,

Yea I started with the Mediacom supported list. I don't want to battle with them anymore than I have to.

I took the router/firewall out of line as normally a port restriction is a function of the router and not the modem. So I just took a notebook down to the basement and plugged straight into the modem. Internet was OK but still could not telnet a cluster server. Can telnet VE7CC.net on 7373 but not 23.

So either the modem is blocking the port or cable company is. Mediacom says they are not and so does Arris. And the support ended there.

The SB6190 is just a modem only so there is no router in it. So when you log in you have option to change PW and logs.

I just ordered a Netgear CM1000 and it should be here Monday. I have just read all kinds of stuff on here about modem issues with the Flex so thought I would make a post.

Previous modem/routers had no issue with 23. I just cant be sure if it stopped working exactly when I upgraded some network equipment or not as the cluster I was using was not a standard port 23.

Rich

W2ECK · January 2020

I had similar problems. Something ( Comcast?) kept causing the modem to revert to default settings and out of Bridge mode. So replaced with a "dumb" modem and haven't had any issues since. The port forwarding instructions reside in the router.

https://www.amazon.com/gp/product/B06XH46MWW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

73 Paul w2eck

Rich McCabe · January 2020

Unfortunately with Mediacom even if the modem is on their list of supported modems they wont help you. All the firmware updates,etc on this device are done for their side. But since you are not paying them a monthly fee for the modem you are kinda on your own.

I believe they call this the between the rock and the hard place. They will send a tech out to look at it but if their cable connection checks out OK its $49.95.

I am pretty sure port 23 dropped when I added this new modem so I would rather throw the money at another modem and try that first.

I mount my modems with velcro as they seem to be disposable.

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Rich McCabe · February 2020

Follow up. The new Netgear CM1000 works perfect. Port 23 now works. So the Arris modem that does not have internal technology to limit ports (according to Arris) apparently does.

73

Looking for new cable modem

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