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HG633 coil whine under load had poor WIFI 5Ghz now on dsl-3782 no coil whine but speed drops

Whizz Kid
Message 72 of 72

When I first switched over to VDSL from ADSL2 I was supplied a HG633 this was working well except I was never happy with the WIFI performance on 5GHz.


Recently the HG633 started to make a high pitch audible noise I believe this was coil whine and started to really become a problem as it is located in the living room.

Internet speeds were stable and largly on the higher end of what what was expected and hardly dropped.

However more recently it did start around the same time as the whine it was getting after the recent contract renewal when we upgraded between 56-63MBps however lately it is strugling to get past 53MBps even after switching of for 30 minutes this didn't get better. I think this has caused the DLM to drop.


A while back we were also supplied a DSL-3782 which was only used when the HG633 had firmware problems before I was enrolled into the testing phase of the HG633 firmware before that was rolled out to all customers. I've started using this again two days ago however I woke up this morning to the biggest drop in some time down to 45MBps after a quick reboot this increased to 50MBps. The WIFI on the DSL-3782 is a huge improvement over the HG633 on 5GHz is much stronger and maintains a somewhat better max speed expected for the network bandwitch for dual band wifi, not perfect but a better result.


I know where to look for speeds which is always on the modem settings pages which is where I base all this knowledge from for speeds of the hardware.


So why at first was it at the maximum advertised and beyond expectations and more recently this has landed on the much lower end of advertised speeds? Fortunatly this is only £2.50 a month on the deal we were offered but when this goes up to £5 I can't justify the benefit of 5MBps for £5 a month so unless this is resolved when the time comes I will return to the old package at only a marginal speed difference.


This is what I always look for and not speedtest results.

Link Rate:

19113/50066 Kbps


I fully understand what I'm looking for with speeds, and because I can not change the DNS for this I can not get speedtest results that come close to what the link rate is showing it falls short by 4MBps down and 2MBps up.


I've now plugged this into the test socket ready for any testing that is required following what seems to be required when support is provided. I do hope this returns to the higher speeds that I had when we first enrolled to the extra fiber speed boost package.


Message 61 of 72

It does, I was in the testing phase for this firmware also before it was rolled out to all customers.



Should I disconnect the 3782 and plug in HG633 today and monitor the speeds and other stats?


Message 62 of 72



Ok, does the HG633 have v2.00 firmware?





Message 63 of 72
HG633 had worse WIFI any suggestions seems a shame to revert back when I've now seen a better WIFI with the 3782? Have settings been looked at, they're must be a reason that can explain why the 3782 is loosing speeds?

Message 64 of 72



As there seems to be 2 different issues, would you like us to send another HG633 router for testing purposes?





Message 65 of 72

Yet a further drop this morning:

Cable Status: Connected
Link Rate: 17101/37856 Kbps
Connection Type: Dynamic IP
Network Status: Connected
Connection Uptime: 0 Day 17 Hour 37 Min 45 Sec

Now this is well bellow the boost minimum and well bellow what I had during the first few weeks with the boost. I've added further message updates over the weekend please also read those.



UpLink / DownLinkSNR Margin:Line Attenuation:Output Power:Data Rate:

6.8 dB / 7.9 dB
4.3 dB / 13.8 dB
7.1 dbm / 12.3 dbm
17101 kbps / 37856 kbps

Message 66 of 72

Woke up again to even worse speeds


SNR Margin: 6.0 dB / 5.8 dB

Line Attenuation: 4.4 dB / 13.5 dB

Output Power: 7.1 dbm / 13.1 dbm

Data Rate: 18039 kbps / 40850 kbps

DSL (Sync) Uptime: 0d:6h:9m:43s


again overnight it lost connection and as a result more speed.


So I will repeat what I've said HG633 coil whine, yet stable connection and to a point speeds but poor wifi compared to the 3782 that I recently changed to but this looses connection overnight and as a result drops speed but has better wifi and is silent.


clearly both modems have different faults its case of taking bad with the good clearly now I am getting speeds bellow the boost advertised speeds and well bellow the 63MBps that it had during the initial weeks of the boost being added. Why are these speeds being taken away from me?


Message 67 of 72
Thanks for the link that got me to the page but it is only part of the problem.

Message 68 of 72
because I can not change the DNS for this I can not get speedtest results that come close to what the link rate is showing it falls short by 4MBps down and 2MBps up.

Have you tried


Now surfing from a Dell Inspiron 3881 running Windows 11 and a Qualcomm QCA9377 Wireless Network Adapter with Sagemcom FAST 5364 router.

Message 69 of 72

Again woke up today to another connection drop and speed loss, just logged into modem to find:

Link Rate: 18543 kbps / 42837 kbps

So I can either live with my HG633 making coil whine with at least a stable speed without drop recently but was better when we setup boost added in initial weeks, and no where near as good as it was when we started this boost during the first weeks. Or use the 3782 which is silent has better WIFI but has disconnects and drops speed while doing so.

I've got a copy of the results during the initial weeks of the boost using HG633:

Upstream line rate (kbit/s): 19997
Downstream line rate (kbit/s): 63368
Upstream noise safety coefficient (dB): 5.8
Downstream noise safety coefficient (dB): 3.6
Upstream interleave depth: 1
Downstream interleave depth: 13
Line standard: VDSL2
Upstream line attenuation (dB): 6.5
Downstream line attenuation (dB): 14.5
Upstream output power (dBm): 7.5
Downstream output power (dBm): 14.1
Channel type: Interleaved
DSL up-time: 1 day 8 hours 40 minutes 13 seconds





While today on the 3782:

UpLink / DownLink

SNR Margin: 6.1 dB / 5.8 dB

Line Attenuation: 4.3 dB / 13.8 dB

Output Power: 7.1 dbm / 13.2 dbm

Data Rate: 18543 kbps / 42837 kbps


Message 70 of 72
Speed did drop before connecting the 3782, it started some weeks ago when the coil whine started on the HG633 around that time. It has got worse in the last two weeks. However the biggest drop did occur overnight two days into using the 3782,

I had performed a few manual resets to try and establish a better connection however I did not action the one that introduced the 45MBps connection I awoke to this morning, this was after the second night of switching over to the 3782. I did notice two connection losses during the day time without me doing anything but mostly I have not been aware of more than three unexpected connection losses after switching to the 3782.

Support Team
Message 71 of 72



I've run a test on the line which hasn't detected a fault, however I can see quite a few re-connections on the line. Is the connection unstable?


Did the sync speed only drop when you connected the 3782 router or prior to this?