Netgear DGN3500 keeps dropping connection

ikeP · September 30, 2019, 2:30am

Few weeks ago I got an old DGN3500 from my relative. I noticed that the device would drop connection regularly, it had a non-up-to-date factory firmware installed so I decided to try installing Openwrt 18.06.4 to see if this would fix the problem, but it did not.

I noticed that during the drops I'm still connected to the modem, but it just drops the ADSL2+ connection (the whole "DSL" stats section shows just all zeros on the main page) and reconnects after a minute or so. I don't have any problems staying connected when using my even older Zyxel p660xxx modem, so I don't think it's a line issue.

I opened the DGN3500 and noticed that the Lantiq chip would get pretty hot during usage, so I crafted a cooler (passive) on it from an old Intel stock cooler. Before adding the cooler, the modem would struggle to keep the connection while doing a 200mb speedtest through testmy.net, but after adding the cooler it can pass multiple 200mb tests in row (those take quite a while on my slow ~15mbps connection).

But the modem still keeps dropping the connection, ~~and it seems to happen pretty often when the line uptime nears 30 minutes, so could it be a WAN lease issue or something (although I think I've seen the line uptime to be almost 2 hours once)?~~

Why I want to use my malfunctioning Netgear instead of the Zyxel: Because of SQM (I have SQM disabled atm tho), and online gaming feels somehow better with the Netgear, even though the ping is basically the same.
Is this just a placebo, or is there more to connection quality in gaming than just ping (choke and packet loss is at 0 on both modems too)? Because I feel like the hitreg is def better when I play CSGO with the Netgear (with the Zyxel I feel like my shots don't register as instantly and I get "prefired" all the time).

Does anyone have similar experiences with the DGN3500 or has an idea what could solve my problem?

ikeP · September 30, 2019, 12:43pm

This is how my DSL status looks while connected:

**Line State:** UP [0x0]
**Line Mode:** G.992.5 (ADSL2+)
**Line Uptime:** 11m 59s
**Annex:** A
**Profile:** -
**Data Rate:** 18.026 Mb/s / 960 Kb/s
**Max. Attainable Data Rate (ATTNDR):** 18.284 Mb/s / 964 Kb/s
**Latency:** 4.0 ms / 2.0 ms
**Line Attenuation (LATN):** 25.1 dB / 13.8 dB
**Signal Attenuation (SATN):** 23.4 dB / 14.3 dB
**Noise Margin (SNR):** 8.4 dB / 7.9 dB
**Aggregate Transmit Power(ACTATP):** 19.9 dB / 10.3 dB
**Forward Error Correction Seconds (FECS):** 20076 / 19
**Errored seconds (ES):** 1 / 0
**Severely Errored Seconds (SES):** 0 / 0
**Loss of Signal Seconds (LOSS):** 0 / 6
**Unavailable Seconds (UAS):** 32 / 32
**Header Error Code Errors (HEC):** 16 / 0
**Non Pre-emtive CRC errors (CRC_P):** 0 / 0
**Pre-emtive CRC errors (CRCP_P):** 0 / 0
**ATU-C System Vendor ID:** Infineon 113.197
**Power Management Mode:** L0 - Synchronized

After losing the connection:
It looks like I start getting a ton of errors prior to losing the connection, especially the HEC error count starts going up like crazy all of a sudden after ~15mins of being connected.

**Line State:** DOWN [0x0]
**Line Mode:** -
**Line Uptime:** 19m 14s
**Annex:** -
**Profile:** -
**Data Rate:** 0 b/s / 0 b/s
**Max. Attainable Data Rate (ATTNDR):** 0 b/s / 0 b/s
**Latency:** 0.0 ms / 0.0 ms
**Line Attenuation (LATN):** 0.0 dB / 0.0 dB
**Signal Attenuation (SATN):** 0.0 dB / 0.0 dB
**Noise Margin (SNR):** 0.0 dB / 0.0 dB
**Aggregate Transmit Power(ACTATP):** 0.0 dB / 0.0 dB
**Forward Error Correction Seconds (FECS):** 2731572 / 26
**Errored seconds (ES):** 96 / 0
**Severely Errored Seconds (SES):** 41 / 0
**Loss of Signal Seconds (LOSS):** 0 / 6
**Unavailable Seconds (UAS):** 45 / 42
**Header Error Code Errors (HEC):** 34753 / 0
**Non Pre-emtive CRC errors (CRC_P):** 0 / 0
**Pre-emtive CRC errors (CRCP_P):** 0 / 0
**ATU-C System Vendor ID:**
**Power Management Mode:** L3 - No power

Now after 17-18mins of being connected I got new kind of connection problem: I can't access internet, but the DSL status still shows that I'm connected, required a reboot to get the internetability back (tried changing DNS, but didn't help).

EDIT:

Now surprisingly at 1h 25m of line uptime, I noticed that my SNR has quite a bit of variation, sometimes it's at 8db, and sometimes it goes up to 10dB. The right one SNR stays consistently at 7.9-8dB

**Line State:** UP [0x0]
**Line Mode:** G.992.5 (ADSL2+)
**Line Uptime:** 1h 24m 45s
**Annex:** A
**Profile:** -
**Data Rate:** 17.979 Mb/s / 976 Kb/s
**Max. Attainable Data Rate (ATTNDR):** 18.092 Mb/s / 972 Kb/s
**Latency:** 4.0 ms / 2.0 ms
**Line Attenuation (LATN):** 25.0 dB / 13.8 dB
**Signal Attenuation (SATN):** 23.3 dB / 14.3 dB
**Noise Margin (SNR):** 10.0 dB / 8.0 dB
**Aggregate Transmit Power(ACTATP):** 19.9 dB / 10.5 dB
**Forward Error Correction Seconds (FECS):** 297544 / 28
**Errored seconds (ES):** 52 / 1
**Severely Errored Seconds (SES):** 0 / 0
**Loss of Signal Seconds (LOSS):** 0 / 6
**Unavailable Seconds (UAS):** 27 / 27
**Header Error Code Errors (HEC):** 294 / 7
**Non Pre-emtive CRC errors (CRC_P):** 0 / 0
**Pre-emtive CRC errors (CRCP_P):** 0 / 0
**ATU-C System Vendor ID:** Infineon 113.197
**Power Management Mode:** L0 - Synchronized

EDIT2:

5 minutes later the I start getting a lot of HEC errors again and I lose the connection (but it reconnected within ~20sec):

**Line State:** DOWN [0x0]
**Line Mode:** -
**Line Uptime:** 1h 30m 46s
**Annex:** -
**Profile:** -
**Data Rate:** 0 b/s / 0 b/s
**Max. Attainable Data Rate (ATTNDR):** 0 b/s / 0 b/s
**Latency:** 0.0 ms / 0.0 ms
**Line Attenuation (LATN):** 0.0 dB / 0.0 dB
**Signal Attenuation (SATN):** 0.0 dB / 0.0 dB
**Noise Margin (SNR):** 0.0 dB / 0.0 dB
**Aggregate Transmit Power(ACTATP):** 0.0 dB / 0.0 dB
**Forward Error Correction Seconds (FECS):** 1784267 / 28
**Errored seconds (ES):** 258 / 1
**Severely Errored Seconds (SES):** 21 / 0
**Loss of Signal Seconds (LOSS):** 0 / 6
**Unavailable Seconds (UAS):** 39 / 37
**Header Error Code Errors (HEC):** 19980 / 7
**Non Pre-emtive CRC errors (CRC_P):** 0 / 0
**Pre-emtive CRC errors (CRCP_P):** 0 / 0
**ATU-C System Vendor ID:**
**Power Management Mode:** L3 - No power

System log:

Mon Sep 30 16:40:30 2019 daemon.notice netifd: wan (1369): udhcpc: sending renew to 195.74.2.54
Mon Sep 30 16:40:30 2019 daemon.notice netifd: wan (1369): udhcpc: lease of xx.xxx.xx.xxx obtained, lease time 7200
Mon Sep 30 17:13:18 2019 kern.warn kernel: [ 5632.040657] leave showtime
Mon Sep 30 17:13:18 2019 daemon.notice netifd: Network device 'dsl0' link is down
Mon Sep 30 17:13:18 2019 daemon.notice netifd: Interface 'wan' has link connectivity loss
Mon Sep 30 17:13:19 2019 daemon.notice netifd: wan (1369): udhcpc: received SIGTERM
Mon Sep 30 17:13:23 2019 daemon.info dnsmasq[1519]: read /etc/hosts - 4 addresses
Mon Sep 30 17:13:23 2019 daemon.info dnsmasq[1519]: read /tmp/hosts/dhcp.cfg01411c - 0 addresses
Mon Sep 30 17:13:52 2019 kern.err kernel: [ 5665.581035] [DSL_BSP_Showtime 914]: Datarate US intl = 947885, fast = 0
Mon Sep 30 17:13:52 2019 kern.warn kernel: [ 5665.586303] enter showtime, cell rate: 0 - 2235, 1 - 2235, xdata addr: 0x82da0000
Mon Sep 30 17:13:52 2019 daemon.notice netifd: Network device 'dsl0' link is up
Mon Sep 30 17:13:52 2019 daemon.notice netifd: Interface 'wan' has link connectivity
Mon Sep 30 17:13:52 2019 daemon.notice netifd: Interface 'wan' is setting up now
Mon Sep 30 17:13:52 2019 daemon.notice netifd: wan (22022): udhcpc: started, v1.28.4
Mon Sep 30 17:13:53 2019 daemon.notice netifd: wan (22022): udhcpc: sending discover
Mon Sep 30 17:13:53 2019 daemon.notice netifd: wan (22022): udhcpc: sending select for xx.xxx.xx.xxx
Mon Sep 30 17:13:53 2019 daemon.notice netifd: wan (22022): udhcpc: lease of xx.xxx.xx.xxx obtained, lease time 7200
Mon Sep 30 17:13:54 2019 daemon.warn dnsmasq[1519]: no servers found in /tmp/resolv.conf.auto, will retry
Mon Sep 30 17:13:54 2019 daemon.notice netifd: Interface 'wan' is now up
Mon Sep 30 17:13:54 2019 daemon.info dnsmasq[1519]: reading /tmp/resolv.conf.auto
Mon Sep 30 17:13:54 2019 daemon.info dnsmasq[1519]: using local addresses only for domain test
Mon Sep 30 17:13:54 2019 daemon.info dnsmasq[1519]: using local addresses only for domain onion
Mon Sep 30 17:13:54 2019 daemon.info dnsmasq[1519]: using local addresses only for domain localhost
Mon Sep 30 17:13:54 2019 daemon.info dnsmasq[1519]: using local addresses only for domain local
Mon Sep 30 17:13:54 2019 daemon.info dnsmasq[1519]: using local addresses only for domain invalid
Mon Sep 30 17:13:54 2019 daemon.info dnsmasq[1519]: using local addresses only for domain bind
Mon Sep 30 17:13:54 2019 daemon.info dnsmasq[1519]: using local addresses only for domain lan
Mon Sep 30 17:13:54 2019 daemon.info dnsmasq[1519]: using nameserver 1.1.1.1#53
Mon Sep 30 17:13:54 2019 daemon.info dnsmasq[1519]: using nameserver 1.0.0.1#53
Mon Sep 30 17:13:55 2019 user.notice firewall: Reloading firewall due to ifup of wan (dsl0)
Mon Sep 30 17:14:02 2019 daemon.info dnsmasq[1519]: read /etc/hosts - 4 addresses
Mon Sep 30 17:14:02 2019 daemon.info dnsmasq[1519]: read /tmp/hosts/dhcp.cfg01411c - 0 addresses

mk24 · September 30, 2019, 3:01pm

The first step to diagnose basic port connectivity issues is try the latest factory firmware, if that still does not work there is a hardware problem.