Wan sensitivity with long network cable runs from Fios ONT

We have been having random wifi drops outs on our stock firmware Linksys EA4500 since our family have been sheltering in place and all working at home during the week, so I thought it a good opportunity to get more exposure to 3rd party firmware and confirm or not that it is the stock firmware that is causing the lockups/reboots.

So I start out this morning backing up current config and downloading both stock firmware (just in case, even though I know that my router has a backup partition) and the only 3rd party firmware that seemed to be compatible with my router - OpenWRT. After uploading the firmware, restarting, and going through the options to get wifi and DHCP setup, I notice that the WAN port has no lights, nor an Rx/IP. MANY web searches later, I had tried putting IP from stock firmware into static WAN IP settings; tried executing "ipconfig /release" from my Window's PC that could get internet with the cable from the ONT plugged into it, then waiting 2 hours to try restarting the router and the WAN interface (with DHCP client changed back to be the protocol); ticking "Use broadcast flag"; unplugging router and giving it 2 hours before plugging it back in; and a few more things I now forget, all to absolutely no sign of life from the WAN port lights or WAN Rx in the OpenWRT interface.

To my utter annoyance I found that on a hunch plugging a 1ft cable between the ONT and the router (Stock firmware works most of the time with a 25ft cat-something run) got the WAN lights working, and an IP, and internet!

Why does my laptop or the stock firmware of this router work through this 25ft cat-something run, and not the blinking OpenWRT firmware?? Is there logs beyond Status -> System Log to explore what udhcpc is doing in between the below log entries that may explain the reason for the non-successful low level connection not allowing the higher level assignment of an IP?

Wed Jan 29 16:20:12 2020 daemon.notice netifd: Interface 'wan' is enabled
Wed Jan 29 16:20:12 2020 daemon.notice netifd: Interface 'wan6' is enabled
Wed Jan 29 16:20:12 2020 daemon.notice netifd: bridge 'br-lan' link is up
Wed Jan 29 16:20:12 2020 daemon.notice netifd: Interface 'lan' has link connectivity
Wed Jan 29 16:20:12 2020 daemon.notice netifd: Network device 'eth0' link is up
Wed Jan 29 16:20:12 2020 daemon.notice netifd: VLAN 'eth0.1' link is up
Wed Jan 29 16:20:12 2020 daemon.notice netifd: Network device 'lo' link is up
Wed Jan 29 16:20:12 2020 daemon.notice netifd: Interface 'loopback' has link connectivity
Wed Jan 29 16:20:12 2020 daemon.notice netifd: Network device 'eth1' link is up
Wed Jan 29 16:20:12 2020 daemon.notice netifd: VLAN 'eth1.2' link is up
Wed Jan 29 16:20:12 2020 daemon.notice netifd: Interface 'wan' has link connectivity
Wed Jan 29 16:20:12 2020 daemon.notice netifd: Interface 'wan' is setting up now
Wed Jan 29 16:20:12 2020 daemon.notice netifd: Interface 'wan6' has link connectivity
Wed Jan 29 16:20:12 2020 daemon.notice netifd: Interface 'wan6' is setting up now
Wed Jan 29 16:20:12 2020 daemon.notice procd: /etc/rc.d/S96led: setting up led health
Wed Jan 29 16:20:12 2020 daemon.notice procd: /etc/rc.d/S96led: setting up led pulse
Wed Jan 29 16:20:12 2020 daemon.notice netifd: wan (1335): udhcpc: started, v1.30.1
Wed Jan 29 16:20:12 2020 user.notice firewall: Reloading firewall due to ifup of lan (br-lan)
Wed Jan 29 16:20:12 2020 daemon.err odhcp6c[1339]: Failed to send RS (Address not available)
Wed Jan 29 16:20:13 2020 kern.info kernel: [   16.241603] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: 
link becomes ready
Wed Jan 29 16:20:13 2020 kern.info kernel: [   16.248480] IPv6: ADDRCONF(NETDEV_CHANGE): br-
lan: link becomes ready
Wed Jan 29 16:20:13 2020 kern.info kernel: [   16.255141] IPv6: ADDRCONF(NETDEV_CHANGE): eth1:
link becomes ready
Wed Jan 29 16:20:13 2020 daemon.notice netifd: wan (1335): udhcpc: sending discover

probably wise to check lower level connectivity stats, while your at it when you switch the firmwares... use a laptop to measure wifi signal strenght between each... ( and verify wanmac is identical on both also )

what sort of info did you get out of the stock firwmare regarding these drops... ?

you did not mention the model? it is kind of relevant...

I guess I didn't elaborate enough. I don't know how to check lower level connectivity stats. As for wifi signal strength, not sure how this relates to the wan connectivity with udhcpc issue?

The stock firmware had very little in the logs, and realistically even if it had not sure much would have allowed me to ascertain if it drops were as a result of a software or hardware issue (when it boils down to it I just need a stable router, which I trusted experiencing stability or not with custom firmware would more quickly help me establish if this were possible with my current router or not).

Model was mentioned in first sentence. Linksys EA4500.

Get a new router.

If that were an option for my current financial situation I would have: 1) Done so, 2) Not posted asking for help with what I have to work with.

Anyone else willing to help with the asked question?

@megabyte, welcome to the community!

You could have a very rare occurrence; and a possibly common one:

  • The 25 ft cable is resonant and causing RF issues
  • The cable was hand-made improperly

Other suggestions:

  • You can try to configure another port on the device as WAN - in hopes it's a port damaged issue
  • Try a cable of another length
  • Couldn't hurt to run swconfig dev switch0 show - and see if there's info
  • Ensure the cable is at least Cat 5 or 5e...as I recall Cat 4 and below were not actually rated for Gigabit Ethernet (in fact Cat 3 and below were rated for telephone). I note this because some Cat 3 cables look like a common network cable with RJ-45 terminated ends.

With gigabit equipment at both ends, all 4 pairs in the cable need to be good. In some cases a faulty cable will fall back to 100 Mb and in some cases it won't, and there is no link. When the link lights do not come on its a rather fundamental problem not something that reconfiguring software is likely to solve.

If you're having what seems like hardware faults with stock firmware, it very likely is a hardware problem. Try a different power supply before condemning the router.

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Hi IIeachii,

First off thanks for replying!

Interesting idea about the cable being resonant. I have a basic understanding of that principle, and so would welcome more information as to how this would affect the signal flowing along a twisted pair cable.

As for the cable, it does look handmade and solid core (not flexible). Knew this when installed but seems until now forgot about how solid core is only meant for little flexing applications. Will look to replace this a.s.a.p.

I saw the LAN port reconfigure as an option as was hoping to not have to take a usable for LAN port out of commission. I will reconsider this preference.

Cable length cannot easily be shortened. It is just long enough to go from Verizon equipment on one end of house to the middle of house which services most things in the house. Extenders aren't on the cards in the near future.

Thanks, will try that command for more info that hopefully leads to a successful troubleshooting avenue.

Per comment on homemade cable above, I am not sure what cat the cable is rated to (no markings) but it looks big enough to be at least Cat 5 rated. However in looking up the difference between Cat 5/5e (and 6) saw that Cat 6 is best for interference and went to look at surrounding power cables to the run. There was a 40A cable touching one part of the Cat run, and another within a few inches. Problem is where Verizon has the fibre coming into the house and where the power cabling is routed through joists/etc won't make it easy to avoid them. Are you aware of how close 40A and less power cabling can be to Cat cable without causing inference, and if crossing it at 90% offset can eliminate or minimise the interference compared to any length traveling alongside, or close to it?

So to word it a different way - one of those lights that flank the tab of a RJ45 socket is the link light, and without at least this one on there is no software communication?

Fault only exist with 3rd party firmware unfortunately. Stock firmware connects fine (but we believe is having issues with the increased traffic of more than one person working from home, hence the desire to see if different software led to a more stable routing experience). This is why it was puzzling that different software on the same hardware would not connect. I have since been informed that to a lower degree than I was aware software is involved in establishing a connection.

It would f*c& it up. No way to tell how the "radio gods" made your cable a real antenna for your singular instance...this is VERY RARE, though.

Then simply lengthen it (or use a ferrite wrap somewhere - this has to be calculated). See the Wikipedia for max length; and highly doubt it's the issue (but a fix is noted in WIki).

The power adapter seems cheapest to check first, as @mk24 suggested.

Any resources you recommend on how to calculate size and where (I assume) the ferrite core should go along the cable?

I will try a different PSU, but I am still stuck on the stock firmware with the same PSU connecting to the WAN connection fine, as well as my laptop. This doesn't seem likely the issue.

Actually, different firmware could potentially demand more or less from the power supply based on the way that it schedules tasks and the hardware loading based on the software design

I’d replace your long Ethernet cable (get a good quality cat6 cable) too, but do these as different experiments so you can identify if one, the other, or both together help resolve the issue.

Do you have an unused gigabit switch (unmanaged is fine)? You could see what happens if you connect that between the fios and router at various physical locations (close to the fios entry point, close to the router, or somewhere in between). You will be able to see if there is any difference or if it reveals connection issues on one side or the other.

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