[Deco XE75 V1.0] Constant "pppd: len < 0" errors every 10s - PPPoE Parser Bug
[Deco XE75 V1.0] Constant "pppd: len < 0" errors every 10s - PPPoE Parser Bug
Hi everyone,
I am experiencing a persistent issue with my Deco XE75 V1.0 (EU) running the latest official firmware 1.4.3 Build 20240926 Rel. 38336.
My ISP is Dimensione (Italy), providing a 2.5Gbps fiber connection via ONT and PPPoE. In the system logs, I see the following error recurring precisely every 10 seconds:
daemon.notice pppd[XXXXX]: len < 0 daemon.notice netifd: internet (XXXXX): len < 0
Impact: While the connection doesn't drop for standard browsing or streaming, these errors cause micro-lags and "packet buffering" on time-sensitive applications, specifically ADS-B receivers and GNSS miners connected via wifi.
Technical Analysis: My ISP’s technical support analyzed the logs and confirmed that this is a known bug in the PPPoE/netifd parser (likely related to LCP Echo Request handling) within the Deco firmware's OpenWrt-based backend. They mentioned that this has been addressed in newer firmware versions for other regions/models.
Troubleshooting already performed:
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Tested MTU at 1492, 1480, and 1472 (no change).
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Disabled IPv6 (no change).
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Replaced the WAN cable with a certified Cat6 (no change).
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The issue persists even with minimal network load.
Since 1.4.3 is currently the latest available version for V1.0 EU, is there a Beta firmware (e.g., 1.4.4 or 1.4.5) or a specific "Lab" release that includes the fix for this PPPoE parser bug?
.
Thank you in advance for your help!
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Decos have been running without drops in the past few days, so that worked fine.
As I understand the issue is not firware fixable, right? Don't think the warranty is still up. will check with the shop. Anyway, works for a temporary fix, but considering the whole situation, the Decos won't be an option anymore, unfortunately.
Thank you for your help, things are working again and that was most important here.
Maybe also include this fix somewhere to be easily found.
Have a nice one
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My be65 is experiencing the same issue, and I'm still looking for the cause. Could you tell me how you resolved it?
daemon.notice pppd[14101]: len < 0
daemon.notice netifd: internet (14101): len < 0
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Hi!
Wouldn't call it a fix, but it worked for me. The xe75 have 3 eth slots on the back. I was advised to connect the main deco eth cable to the middle slot, no. 2 in my case. I don't know if it will stop working if i use any of the other slots, but i'm not changing anything until a better solution.
Also, maybe usefull. I switched the decos to be APs and got a separate router to connect to the internet. Only the main deco is wired to the router. The rest are wireless.
hope it helps
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@GKVDR
@David-TP
I've tried many methods, but I still can't resolve the error message; it continues to appear every ten seconds.
Thu Mar 26 00:10:32 2026 daemon.notice netifd: internet (2766): len < 0
Thu Mar 26 00:10:42 2026 daemon.notice pppd[2766]: len < 0
PPPOE撥接和浮動依然有問題
主 Deco BE65
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