RM500U Low speeds on 5G

Technical Subjects
1

Hi,
I am new to this module. I have the following RM500 module
AT+GMR
RM500UCNVAAR03A10M2G_01.001.01.001

OK
AT+GMM
RM500U-CNV

OK
ATI
Quectel
RM500U-CNV
Revision: RM500UCNVAAR03A10M2G

It is working as rndis mode

When connected to 5G, getting very low bandwidth of ~100kbps only.
Config
AT+C5GREG?
+C5GREG: 0,1

OK
AT+QNWINFO
+QNWINFO: “NR5G-SA”,405861,“NR N78”,634080

AT+QCFG=“nat”
+QCFG: “nat”,0
AT+QCFG=“usbnet”
+QCFG: “usbnet”,3

AT+QCFG=“usbnet_max_dl_pkts”
+QCFG: “usbnet_max_dl_pkts”,7

Question : This firmware supports usbnet_max_dl_pkts to max value of 7. Is this causing low download speeds?
Snapshot of the speed:
curl -o /dev/null http://speedtest.tele2.net/10MB.zip
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
11 10.0M 11 1211k 0 0 67533 0 0:02:35 0:00:18 0:02:17 105k

2

…Additional Info
AT+QENG=“servingcell”
+QENG: “servingcell”,“CONNECT”
+QENG: “LTE”,“FDD”,404,45,2D53720,172,240,1,3,3,1B90,-91,-19,-56,-7,3,8,33
+QENG: “NR5G-NSA”,404,45,710,-83,2,-5,627936,78,0,1B90,1
AT+QNWPREFCFG=“nr5g_band”
+QNWPREFCFG: “nr5g_band”,1:78

3

It seems working on Linux. NCM is better than RNDIS.
AT+QCFG=“usbnet”,5

4

I have the same issue, even though I’m already in NCM mode (RM500U-CN). I’m using a Xiaomi R3P router running Rooter ROM. My FW: RM500UCNAAR01A20M2G_01.001.01.001.

5

So are you seeing low download speeds even with Rooter ROM?

6

Yes! When I checked, I could detect 5G signals, but I couldn’t actually use 5G (when I put the SIM card into a phone, 5G works normally).
My firmware: RM500UCNAAR01A20M2G_01.001.01.001
My IMEI: 868227051469641
I’m not sure if it’s because my firmware is outdated. Please help me.

7

For antenas connected?
Please also make sure it is USB 3.0 rather than USB 2.0.

8

That’s too low. Normally even without extra settings it should be more than 200Mbps with 5G network. For Quectel test, it should be over 700Mbps.

1 Like
9

Working for me in RNDIS mode as well, (able to get IP address on the interface and ping works)
But the download speed is too less, when I try iperf. getting 100kbps only

10

For Linux, there is bug with RNDIS mode, NCM works much better than RNDIS.

11

Yes antennas are connected but is it due to poor SNR ?

+QENG: “LTE”,“FDD”,404,45,2D53720,172,240,1,3,3,1B90,-91,-19,-56,-7,3,8,33
404,45 → MCC=404 (India), MNC=45 (Airtel)

RSRP -91 dBm → fair/good signal

RSRQ -19 dB → very poor quality (network congestion or interference)

SINR -7 dB → unusable (must be >0 for decent throughput; good is >10 dB)

So it seems usable LTE signal power, but terrible quality (RSRQ/SINR) → this is why throughput is low ? But how to get better SNR

12

It is in LTE network and the signal is not good and not bad.
If there is 5G network in your area, all the four antenna should be connected.
It is Linux or Windows? How you test the speed and performance?

13

Hello ,
Yes All 4 antennas are well connected.
I am running the Openwrt 24.02 with Linux 6.6.86.
To test the speed I recently connected the ethernet port of the device to my laptop (and internet routed from the RM500U on the device) and ran speedtest. Maximum I am getting 2Mbps.

image
image1127×440 39 KB

14

OK. Please set the modem to NCM mode first.

15

I tried NCM.
With LTE only, speeds are 20-30Mbps. While with LTE+NR5G-SA, same issue of 2Mbps max.

16

The UE is currently camping on an NSA network instead of an SA network.
Under normal LTE conditions, the downlink throughput is only 20–30 Mbps, which is below the expected level.

I think it is switching from LTE and NSA and in some time maybe it lose connection.

17

Even with NSA, (in NCM mode ) only 2Mbps is what I am getting max.
AT+QENG=“servingcell”
+QENG: “servingcell”,“CONNECT”
+QENG: “LTE”,“FDD”,404,45,2C41320,56,240,1,3,3,1B90,-83,-17,-57,-12,5,12,39
+QENG: “NR5G-NSA”,404,45,51,-83,-1,-7,627936,78,0,1B90,1

My operator supports NSA only.

So summary
RNDIS Mode – Both LTE Only and LTE+NR5G-NSA stucks at 2Mbps
NMC Mode – LTE Only achieves 20-30Mbps, while LTE+NR5G-NSA stays at 2Mpbs. :frowning:

18

It need some logs for analysis. but I am sorry I am not familar with that.
Does the operator only support N78? As I guess, it is switching and not stable.

19

Update:
Mode: NCM
After trying several times throughout the day it seems that the low throughput is due to network conditions during peak/non-peak hours. During late night testing I am able to get better throughputs ranging 150Mbps to even 300+ Mbps. So I think, as suggested by you, NCM mode helped me as I have not altered any other settings.
Really appreciate your help. Thanks a lot !

1 Like
20

If it is USB 3.0 I think it is not the best as it should be.