I am running the Mango GL-MT300N-V2 as a WAN2 failover behind my OPNsense, which is my main router. My Mango has a E3372 LTE USB Stick in Tethering Mode connected and technically it works fine so far. So I can use the connection from my networks as well via an access point, when I spin it up on the Mango itself. The Mango runs the newest default firmware (3.212 with Compile Time 2022-04-07 16:38:46) and has auto update turned off.
My problem is that the traffic in just stand-by is about 800 MB per month, which is way more than planned via LTE as a plan B connection. So there was no usage of the fallback failover setup and I analysed traffic between my OPNsense and my Mango, which was only about <100MB for availability ping etc. what is the Mango doing behind the lines? Are there any other tools or packages regularly updated? Is there anything else I can turn off? I would like to keep the traffic to an absolut minimum.
Any suggestions?
Actually it is up- and down-traffic summarized (see German screenshot)
My OPNsense is connected to the Mango LAN and this has the LTE Stick in Tethering mode connected via USB. Further on OPNsense sends a ping every 3 seconds to an IP in the web via this connection just to ensure the WAN2 connection is up, this should mainly be responsible for most of the upload traffic (and likewise download), but there is nothing else downloading.
I could - for a worst case test - disconnect the LAN cable to see only the Mango being online, but maybe, someone already has an idea about hidden cronjobs etc. constantly checking for something, that I could turn off?
Ok, that sounds now like the right direction to look at. NTP in general is fine, as long as I can break it down to sync e.g. once a day somewhere? System clock should not be that bad, I guess?
And mwan3 is unknown to me, seems to be some load balancing module, why does this one automatically generate traffic when there is only one WAN connection used and is there a chance to turn this off somehow or do I require it to have LTE/Tethering WAN working?
OK, I made some research here and I found on [OpenWrt Wiki] mwan3 (Multi WAN load balancing/failover) to be able to modify/use the “interval” parameter. When I check the current default config (/etc/config/mwan3) there are two relevant tethering entries in the config:
[...]
config interface 'tethering'
option enabled '1'
list track_ip '8.8.4.4'
list track_ip '8.8.8.8'
list track_ip '208.67.222.222'
list track_ip '208.67.220.220'
option family 'ipv4'
option reliability '2'
option count '1'
option timeout '2'
option interval '5'
option down '3'
option up '8'
[...]
config member 'tethering_only'
option interface 'tethering'
option metric '3'
option weight '3'
As I have Tethering as my only WAN (no WAN cable connected), I would assume, this is the one to go and with the current setup, there is a ping every 5 seconds according to documentation.
When I adjust this value to e.g. 60 or even 300, it should already minimize it, but I cannot really fully turn it off as this is part of the principle, can I?
Since this is a feature that I never use on my travel routers, and it sends out large numbers of ping packets, which is something I really do not want my routers doing, I always just remove it using ssh and the command:
opkg remove mwan3
If you look through past posts in this forum, you will find multiple people have complained for various reasons that mwan3 should have a setting in the main GL iNet GUI to turn it on/off and it should be off by default.
OK, I will try without it and have removed it as suggested. Let’s see if this dramatically changes it.
Thank you two for your support so far. And I agree, it should be more transparent and adjustable in the UI; before this discussion I was not even aware of this service.
Is there anything else I can do to optimize the stand-by load or other services like suggested NTP? Here I did not find a config and how often time is synced. But I am open for any further suggestions.
The ntp protocol seems to not be too chatty, and as WIFI and other services require accurate time, I would not disable it. The MT300N-V2 does not have a battery backed up clock and is totally dependent on ntp for setting and keeping the correct time.
Make sure Auto-upgrade, DDNS, and GoodCloud services are turned off.
I don’t think Luci is loaded by default any more on the MT300N-V2 or any of the routers with only 16MB of FLASH. To install Luci just to disable something seems like overkill and can run you out of FLASH space. This really needs to be added to the main GL iNet menu. Maybe in 4.x?
If you do cannot install LuCI, then you can use SSH to delete the startup link to the mwan3 script, which will not remove the package and can be re-enabled again if necessary:
rm /etc/rc.d/S*mwan3
I have doubts that mwan3 consumes ~800MB data per month.
My Asus main router has a Traffic Analyzer (I think it is licensed from Trend Micro), so I obtained statistics on the background traffic from from idle GL-AR750S, GL-MV1000W and GL-AXT1800 routers, all with mwan3 and ntp running and no client devices, openVPN, wireguard, nor ddns.
Over 24 hours, all 3 routers generated consistent download/upload traffic of 230-240 KB per hour for a total of 5.44-5.48 MB per day, of which >99% are ICMP (pings). At this rate, background traffic would be ~170 MB per month that is consistent with the post by alzhao .
Even if it was 1 packet a day, I feel that there should be an easy way from the main GUI to turn off a service that is not needed by most users. Some services like DNS and NTP need to be turned on by default, for basic router functionality, but a service that is for WAN fail-over, that many users will never use, that continually pings Google servers, I feel should not be on by default. There should either be a switch in the main GUI to turn this function on/off, or the router should only turn this on if there are two or more WAN paths configured on that router.
