Low WiFi speed to internet when using PPOE to ADSL modem

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DD-WRT Novice

Joined: 30 Aug 2019
Posts: 11

PostPosted: Sat Sep 14, 2019 16:58    Post subject: Low WiFi speed to internet when using PPOE to ADSL modem Reply with quote
A bit of an unusual one this....

WNDR3700V1 running DD-WRT v3.0-r40890 std (09/03/19)

Its WAN port is connected to an ADSL modem and the DD-WRT is set up for PPoE and is able to connect to the internet fine through the external DSL modem.

I have known for a long time that any internet speedtest using a mobile device connected to either 2.4GHz or 5GHz always produced a speed of about half of that reported by wired PC's using the same speedtest. A PC will report a D/L of about 70MB/s and U/L of about 18 Mb/s

My ISP's connection is a nominal 76MB/s, so all looks good to me.

However, using either of the WiFi connections, the D/L speed is consistently about 25Mb/s and U/L about 16 Mb/s on 5GHz and 12 Mb/s D/L and 14Mb/s U/L on 2.4GHz.

If I used my ISP's router to connect to the internet and replace the old DSL modem as the newer router is both modem and router, and configure the WiFi, I can get 60Mb/s on 5Ghz and 50 Mb/s on 2.Ghz.

Now here's the kicker......

I turned off the wifi on the ISP router and configured that to be my main router. I then set up DD-WRT to be an AP and turned off the WAN PPoE. On a wired connection throuh the Dd-WRT router the speed as as before (but now going through the other newer router). But now with PPoE turned off, the DDW-RT router connected my Wifi for me to get the same results as via the ISP router, i.e. 60 Mb/s and 50Mb/s D/L speeds but through my old router.

Without changing any wifi settings, I turned my DD-WRT back into its original main router roll and turned on PPoE to connect to the old DSL modem and took out the ISP router. BAM! Wifi speeds immediately dropped again. No settings will get me connected via WiFI with the speeds that I had when PPoE was turned off.

Is this a known problem, or have I missed something?
Per Yngve Berg

Joined: 13 Aug 2013
Posts: 5171
Location: Akershus, Norway

PostPosted: Sat Sep 14, 2019 18:29    Post subject: Reply with quote
Check the line speed of the modems.

One modem may be ADSL and the newer VDSL.
DD-WRT Novice

Joined: 30 Aug 2019
Posts: 11

PostPosted: Sat Sep 14, 2019 20:16    Post subject: Reply with quote
Per Yngve Berg wrote:
Check the line speed of the modems.

One modem may be ADSL and the newer VDSL.

I have a FTTC broadband connection.

The newer modem/router is ADSL, ADSL2+, VDSL2 and Fibre.

The old modem is a VDSL2. So that should not be the problem!

As a test, I flashed the Netgear back to its factory image got from the Netgear site. Set it all up fine including PPoE for the WAN and old router.

Not only did I get a slightly higher speedtest through the old connected modem, (73 Mb/s), the 5Ghz WiFi got a 69Mb/s test as well. So looks like a DD-WRT issue with this modem because 'stock' works fine.

As a double test, I will reflash to the latest DD-WRT factory image and restup again to see if the issue is back or not.

Joined: 16 Nov 2015
Posts: 2910
Location: UK, London, just across the river..

PostPosted: Sat Sep 14, 2019 20:26    Post subject: Reply with quote
tell us your wi-fi settings...
clients might need driver update...
witch test you do...
many other questions about details...
im in UK and using pppoe and i can see full speed...
of 75Mbit or 35 Mbit the connections i have...
i use
BT Openreach Huawei EchoLife Hg612 3b in bridge mode and DDWRT with PPPoE...
i do have a NAT, DNS&DHCP and ect....

TP-Link WR740Nv1 ------DD-WRT 33772 BS WAP/Switch (wired)
TP-Link WR1043NDv2 ----DD-WRT 41369 BS (AP,PPPoE,NAT,AD Blocking,AP Isolation,Firewall,Local DNS,Forced DNS,DoT)
TP-Link WR1043NDv2 ----DD-WRT 41321 BS (AP,NAT,AD Blocking,Firewall,Wi-Fi OFF,Local DNS,Forced DNS,DoT)
TP-Link WR1043NDv2 ----Gargoyle OS 1.11.0 (AP,NAT,QoS,Quotas)
2x Netgear R7800 -------DD-WRT 40270M 4.9 Kong (AP,NAT,AD-Blocking,AP&Net Isolation,VLAN's,Firewall,Local DNS,DNSCrypt-proxy v2 x2)
Netgear R7000 -------DD-WRT 40270M Kong (AP,NAT,VLAN,AD-Blocking,Firewall,Local DNS,Forced DNS,DoT)
Stubby for DNS over TLS I DNSCrypt v2 via Entware by mac913

Joined: 03 Jan 2010
Posts: 7102
Location: YWG, Canada

PostPosted: Sat Sep 14, 2019 20:36    Post subject: Reply with quote
cpu's limit
LATEST FIRMWARE(S) || Qualcomm Atheros Wi-Fi Settings Guide || Qualcomm Atheros Repeating

[X86-64] Haswell i3-4150 ------------> DD-WRT v3.0-r41358 std
[QUALCOMM] R7800 -----------------> DD-WRT v3.0-r40270M kongat
[QUALCOMM] DIR-862L --------------> DD-WRT v3.0-r41369 std
[QUALCOMM] WNDR4300 v1 --------> DD-WRT v3.0-r41369 std
[QUALCOMM] DIR-862L --------------> DD-WRT v3.0-r41369 std
[BROADCOM] DIR-860L A1 ----------> DD-WRT v3.0-r40634 std

BrainSlayer wrote:
we just do it since we do not like any restrictions enforced by stupid cocaine snorting managers

If you use DSLReports please enable hi-res bufferbloat.

Sigh.. why do i exist anyway..
DD-WRT Novice

Joined: 30 Aug 2019
Posts: 11

PostPosted: Sun Sep 15, 2019 14:14    Post subject: Reply with quote

I flashed back to stock Netgear using the latest IMG file off their site. Once set up with the basics, the WiFi speed was fine on both 2.4 and 5.

So I flashed to the earliest DD-WRT first (using TFTP). Once set up, all was good. WiFi speeds fine. Mmmm.

Did a webflash to the latest version and did a full factory reset. A quick and basic setup and all was fine too, with WiFi showing no sign of issues.

I made a note of the WiFi settings and then I restored a backup of the settings I'd made previously. Oh. WiFi speed drops. I checked the WiFi settings and changed them to what they were on the factory default reboot. Still no joy. Speed was affected. Sad

Beginning to think there's a corruption in the settings somewhere, and/or beginning to think it may be either the firewall script or the USB attached to the router with the USB switched on in the control panel.

(1) Factory reset and manually re-enter all the settings (including a Startup script for FreeDYNS and an ARP setting fro broadcasts on for WOL from the WAN). Did not setup firewall script, nor enabled USB, but enabled DNSmsq and sorted that. RESULT: WiFi working fine.
(2) Enabled USB and auto mount. Reboot router. RESULT: WiFi is fine.
(3) Saved settings in case next step (Firewall script) screws things up!
(4) Entered the Firewall script. Saved and rebooted. RESULT: All OK - WiFi is fast.
(5). Enabled all the other settings that I remembered I had such as Syslog, Secure Shell, SSH, Telnet, Remote Web access, CRON etc. RESULT: All OK.
(6) Saved all settings!!

So, looks like there was some corruption along the way because a restore of the old settings file reproduced the error, but a manual re-entry didn't break anything. Thank heaven!

Sorry for the false alarm! If in doubt, reset and manually re-create!
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