MC7455 produces differnt speeds in differnt devices?

[packlet]

Hi, first post here, so please be kind and/or point me at a better forum for this discussion. TIA.

I have an MC7455 modem card (with generic FW, I believe) connected to a pair of antennas using a Three UK SIM card (for now, connects roaming to local AT&T tower, typically bands 2 & 12).

When I use the modem connected (via USB adapter) to a TP-Link Archer C7 v5 (with Rooter/Golden Orb and all default settings), I get some 60-90Mpbs down and ~21Mpbs up. Not shabby, I guess.

However, when I put the same modem into a Mikrotik RBM33G (also with Rooter/GoldenOrb), I only get up to ~30mbps down (about the same 20-21Mbps up).

Wondering what could explain the 2-3x difference in download speeds using the same SIM/modem/antennas on the two devices. They both show connections on the same LTE bands and both indicate active CA when running speedtests. Could it be solely due the extra CPU/memory "horsepower" of the TPlink router? Or perhaps the TPlink somehow is configuring the modem differently to achieve better download speeds? Can anyone offhand explain this, or perhaps suggest how to go about determining what's causing this difference in performance?

I'd prefer to use the smaller form-factored/cheaper RGM33G (or even the RGM11G) for my project, though if the TPlink will always perform better, I'll stick with that...

TIA, Paul.

[Didneywhorl]

Hello, welcome!

Are you testing both via ethernet connection to a pc?

[mtl26637]

How is it connected to the RBM33G? Did you install in one of the internal slots or did you connect via usb port? I think I ended up running mine in the pcie slot closest to the outer edge of the board. If you want usb3 speeds you will have to run it via usb port as the pcie ports are usb2 at best. Might make sure your usb port jumper is in the correct spot also, take a look at the manual and it will explain what the jumper does and how it all ties together with usb2/usb3 and which pcie slot it affects and such. I'm sure its just something small, these little boards are really nice imo.

[packlet]

- yes, I connect to both the TPlink and the RBM33G via Ethernet

- in the RBM33G, i place the modem in the left-most slot, furthest from the USB port. I'm aware of the jumper to disable USB2.0 in favor of the middle pcie slot, but i'm not using either of those.

- I would think USB2's max speed of 480Mbps would not be a bottleneck at the speeds I'm seeing (under 100Mbps),
and the USB port (with mpcie adapter) used on the TPLink is also USB2.0, yet provides 2-3x the DL speeds...

if it helps, here are some cut/past of device status pages and AT status commands taken while running speedtests:

on rbm33g, i get ~31 Mbps down and ~21 up:

System
Hostname
ROOter
Model
MikroTik RouterBOARD M33G
Architecture
MediaTek MT7621 ver:1 eco:3
Firmware Version
GoldenOrb_2021-09-02 ( OpenWrt 19.07.6 )
Kernel Version
4.14.215
Local Time
2021-09-22 21:15:28
Uptime
0h 1m 35s
Load Average
1.01, 0.40, 0.15


at!gstatus?
!GSTATUS:
Current Time: 704 Temperature: 33
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Attached
LTE band: B2 LTE bw: 20 MHz
LTE Rx chan: 800 LTE Tx chan: 18800
LTE CA state: ACTIVE LTE Scell band:B12
LTE Scell bw:10 MHz LTE Scell chan:5110
EMM state: Registered Normal Service
RRC state: RRC Connected
IMS reg state: No Srv

PCC RxM RSSI: -21 RSRP (dBm): -56
PCC RxD RSSI: -32 RSRP (dBm): -67
SCC RxM RSSI: -19 RSRP (dBm): -50
SCC RxD RSSI: -11 RSRP (dBm): -44
Tx Power: -21 TAC: 8B38 (35640)
RSRQ (dB): -13.1 Cell ID: 0A341F08 (171187976)
SINR (dB): 6.2


OK



On TP-Link, I get 98+ Mbps down and ~21 up.

System
Hostname
ROOter
Model
TP-Link Archer C7 v5
Architecture
Qualcomm Atheros QCA956X ver 1 rev 0
Firmware Version
GoldenOrb_2021-08-15 ( OpenWrt 19.07.6 )
Kernel Version
4.14.215
Local Time
2021-09-08 22:31:15
Uptime
0h 19m 58s
Load Average
0.59, 0.67, 0.62

on tp-link, get 98 down, 21 up...

at!gstatus?
!GSTATUS:
Current Time: 268 Temperature: 31
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Attached
LTE band: B2 LTE bw: 20 MHz
LTE Rx chan: 800 LTE Tx chan: 18800
LTE CA state: ACTIVE LTE Scell band:B12
LTE Scell bw:10 MHz LTE Scell chan:5110
EMM state: Registered Normal Service
RRC state: RRC Connected
IMS reg state: No Srv

PCC RxM RSSI: -20 RSRP (dBm): -55
PCC RxD RSSI: -31 RSRP (dBm): -66
SCC RxM RSSI: -23 RSRP (dBm): -52
SCC RxD RSSI: -11 RSRP (dBm): -44
Tx Power: -22 TAC: 8B38 (35640)
RSRQ (dB): -12.8 Cell ID: 0A341F08 (171187976)
SINR (dB): 6.2


OK


How could i determine if the TPlink is setting the modem up differnetly than the Mikrotik? history of AT comands sent to it, i guess is what i'm looking for? The modem/DEBUG page only shows a limited scrollback buffer...

[mtl26637]

- in the RBM33G, i place the modem in the left-most slot, furthest from the USB port. I'm aware of the jumper to disable USB2.0 in favor of the middle pcie slot, but i'm not using either of those.

- I would think USB2's max speed of 480Mbps would not be a bottleneck at the speeds I'm seeing (under 100Mbps),
and the USB port (with mpcie adapter) used on the TPLink is also USB2.0, yet provides 2-3x the DL speeds...

How could i determine if the TPlink is setting the modem up differnetly than the Mikrotik? history of AT comands sent to it, i guess is what i'm looking for? The modem/DEBUG page only shows a limited scrollback buffer...

Was just brainstorming as to what could cause this. My first go to would be how the device was setup to communicate and what drivers etc.? The signals look almost identical so not sure what it could be at this point. Might compare syslogs and see if anything stands out. As for AT logs, I think there is a file in the /tmp folder that has a bit of history of sent commands if I remember correctly but dont recall the name of the file. You would need to ssh into the device and look in the tmp folders, you would know it when you seen it pretty sure.

[mtl26637]

Just remoted into my rbm33g at home and the file I was thinking of is 'atlog' but it looks like it only stores recent history. Maybe you would need to enable logging to catch all commands from startup but not sure. Also, on the debug page, might scroll down below the debug output and compare device/driver settings on both systems. Maybe something there will stand out? Are both setups using same apn settings?

[Didneywhorl]

Honestly it shouldn't be that far off but the Atheros versus Mediatek is definitely a factor in performance.

[packlet]

Just noticed a difference in the default custom firewall rules on the Rooter/OpenWRT versions for each device. The Rooter version installed on the TP-link has the TTL=65 iptables rules DISabled, while the Mikrotik version has it ENABLED.

Odd, as I would expect 'fixing' the TTL on the WAN side might prevent the ISP (Three? or AT&T, since I connect to their tower for roaming?) from detecting/throttling 'hotspot' usage (which is essentially what I'm doing with my PC behind the rooter device.)

So I played with that setting a bit, disabling it on the Mikrotik (got WORSE perf, not surprisingly) and enabling it on the TPlink (also worse download, go figure...) Maybe I didn't properly restart the firewall after making changes (the UI seems a bit vague about that)

Or maybe it's an artifact of my Three SIM card (that I'm only using as I had some GB leftover from a recent trip to Europe).
Anyways, I've now exhausted my Three data with speed tests (ha!) Will test some more with an AT&T ipad SIM (arriving any minute) and see if I get the same perf diffs or not on that plan...

[packlet]

OK, all seems well now. I have a working unlimited AT&T tablet plan SIM and I'm getting similar speeds on 3 different devices, a TP-link Archer C7v5, a MikrotikRBM33g, and an RBM11G, all on latest Rooter pre-release build (from 9/17). I don't know if it was equalizing the builds on the units, or simply the time of day or cell tower congestion or speedtest's choice of endpoint, but I'm now seeing speeds in the 45-60mpbs range down on all of 'em. The TTL override settings seem to have no effect on this plan. I have them all on the same LAN (with dhcp disabled) and simply toggle my default gateway (after moving the modem & sim card) to swap between them...

Good stuff here! thanx to all! cheers, Paul.

PS Now to see if there's anything I can do about the plan's rate-limiting of video content to 1.5Mbps (about 480p). HBOmax looks a lot better over our home fiber (Sonic) than the AT&T wireless...