Bridged CODA-4582U Modem WAN Port 1 keeps dropping to 100Mbps

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the_big_v
I've Been Around
Posts: 1

Bridged CODA-4582U Modem WAN Port 1 keeps dropping to 100Mbps

Hi everyone!

 

Would really appreciate some help, I'm starting to pull my hair out.

 

Set-up:

CODA4582 (Bridged) >Ethernet> EERO Pro 6 gateway (meshed with 2 other Pro 6 in wireless mode) > Gigabit switch > lots of stuff

 

Problem:

I have Gigabit Internet and under normal circumstances I get speeds of ~980 Down / ~35Up when measured from the EERO.

Sporadically, my internet speeds will drop and its very noticeable when it dose.  I will perform a speed check from the EERO and it will show 95 Down / 35 Up.

 

What I have come to notice during troubleshooting is that when this happens, the Port on the CODA flashes Green (100Mbps)  instead of its usual Orange (1000Mbps).  Power cycling the modem will solve the problem.  Sometimes for an hour, sometimes for a day, at most a week.  But it will always re-occur.

 

Rogers tech support is telling me that this is likely Bridge Mode related and that I should run the Modem in regular Gateway mode.  I don't want to do this, I use a VOIP office phone at home as well as a remotely accessible NAS, both of which would become problematic with double NATing.

I was also told by Rogers tech support that in bridge mode only Port 1 is available for use, so I would be unable to use Ports 2,3 or 4.

 

Things I have tried:

Modem swapped

Have been told that the modem firmware is up to date

EERO firmware up to date

Ethernet cable swapped

 

Does anyone have any ideas? ✌️

 

*Added Labels*

stepy2015
I Plan to Stick Around
Posts: 115

Re: Bridged CODA-4582U Modem WAN Port 1 keeps dropping to 100Mbps

Is there a way to force the port speed on the eero?

Datalink
Resident Expert
Resident Expert
Posts: 7,197

Re: Bridged CODA-4582U Modem WAN Port 1 keeps dropping to 100Mbps

@the_big_v your modem issues are certainly odd to say the least.  I run my 4582 in Bridge mode with an ASUS RT-AX86U behind it and its rock solid.  Fwiw, when the 4582 modems were first released, there were issues with the modem's wifi causing EMI issues with the modem's cable tuner, resulting in less than stellar performance.  The modems were cycled thru a modification program to add more shielding to the cable tuner.  Since then the production modems have all had increased shielding over the cable tuner.  

 

Now, it sounds like you have a slightly different problem, but, the observations make me wonder how close the EERO Pro 6 gateway is to the modem?  They should be several feet apart in order to prevent any EMI issues between the follow on router and the modem.  Our AX86U is about 10 feet from the modem with other bits and pieces of equipment between the two and I've never had any issues with the modem's stability on the LAN side and the WAN side is also very stable.  

 

Fwiw, the modem will support two routers or devices, each running their own IPV4 and IPV6 addresses when the modem is running in Bridge mode.  This results in two completely independent networks running off of the modem.  That capability has historically been available for all of the previous Hitron modem models.  This might be of interest for home office purposes given that you're running a VOIP phone. 

 

If you connected two routers to the 4582 (in Bridge mode), the CMTS, thru the modem will provide each router with individual IPV4 and IPV6 addresses.

 

To do that, simply connect the second router to the modem, power it up and wait for about two to three minutes for the CMTS and modem to issue the router its IPV4 and IPV6 addresses.  If for some reason the CMTS and modem don't want to co-operate, leave the routers connected and powered up and reboot/restart the modem.  You can simply pull the power from the modem, wait for 10 to 15 seconds and plug it back in to force a modem restart.  If the CMTS and modem behave as they should, after the restart, each router should have its own IPV4 and IPV6 addresses and each one should be running its own independent network.  The modem does not provide any cross-over capability from one router to the other, or from one device to another when the modem is in Bridge mode.

 

If in the event that the CMTS and modem don't want to play nice and issue both routers their IPV4 and IPV6 addresses:

 

1. disconnect the first router, which should already have its IPV4 and IPV6 addresses. Leave the second router connected and powered up.

 

2. Reboot/restart the modem. After the reboot/restart, the second router should then have an IPV4 and IPV6 address.

 

3. Leave the second router connected, reconnect the first router and power it up.  The CMTS and modem should assign the first router with its IPV4 and IPV6 address. If not, reboot/restart the modem.  After the reboot/restart, both routers should then have their IPV4 and IPV6 addresses.

 

Also note, the statement that the 4582 only provides port one as the operational port when the modem is in Bridge mode is categorically wrong.  All ports are available.  I've used ports 4 and 3 (bottom two ports), in that order for the last 4+ years without any problem.  You can disable ports on the 4582 by logging into the modem kicking it into Gateway mode, and then navigating to the ADVANCED .... SWITCH SETUP tab.  There is only one tab in the ADVANCED selection.  All four ports are listed and you can disable any of them.  When you switch the modem back to Bridge mode, the modem will retain that selected setting, so, if you disable ports 1 and 2 or other ports in Gateway mode, then ports 1 and 2 or other ports will be disabled in Bridge mode.  I've run that configuration for the last 4+ years, again without any issues.  

 

So, given the modem swap, the only thing that I can think of is an EMI issue between the modem and the EERO Pro, or the possibility that the modem doesn't like something that the EERO Pro is doing, causing a speed drop. 

 

Installing a Cat 7 cable might take care of EMI issues if in fact the EERO Pro is somehow inducing an EMI spike on the connecting cable.  I don't believe that should ever happen, but, never say never.  Cat7 and Cat8 cables are fully shielded, and referred to as Shielded / Foiled Twisted Pairs (S/FTP).  What this means is that not only does it have an overall braided shield, but also each individual pair is foil shielded as well.  From what I remember reading Cat 7 cables are shielded end to end, meaning that the braided shield is connected to the metallic RJ-45 connectors.  Cat 8 cables are built that way.  So, that might be food for thought, running a Cat 7 cable between the modem and EERO Pro.  

 

Do  you happen to have a small unmanaged switch that you can run between the modem and EERO Pro 6 gateway for test purposes.  If nothing changes, ok, nothing ventured, nothing gained.  But, if the speed drops stop altogether, then there is some issue between the modem and EERO Pro, question is, what is it?  I'd try a small unmanaged switch first, if you happen to have one around.  

 

Are you running IPV6 in the EERO Pro and if so, have you tried disabling it to see if it has any effect?

 

You are correct in your observation of the modem's connected port LEDs at the back of the modem.  They should remain flashing Amber for a 1 Gb/s connection rate between the modem and connected device port.  It shouldn't drop down to a flashing Green indicating a 10/100 Mb/s connection rate.  

 

Ok, that's all that I can think of for now.  This is certainly a head scratcher.  My guess is either an EMI issue or an occasional protocol issue of some type between the modem and the EERO Pro.