I need to open a new topic about this router/modem because I didn't find a good solution.
Even if this isn't my first OpenWRT router, I'm new with this distro.
I write everything so, maybe, it can be useful also for other users with the same hardware.
My need is a modem with 4G to use it predominantly only with LTE connection.
After some research here in Italy, I found this Tp-Link TL-MR6400 v5 that I bought after I found the page about this here on the OpenWRT's site and forum.
Received it, I didn't try it with the stock firmware and flash directly with the right image:
with WAN connection it works fabulously, with LTE no.
First problem: LTE module didn't work.
After installed the uqmi package and stuff about this (https://openwrt.org/docs/guide-user/network/wan/wwan/ltedongle),
the SIM didn't connect with provider's network.
So I patched the file "/lib/netifd/proto/qmi.sh" as indicate here -> Enabling TL-MR6400 v5 LTE
The SIM connect to the network but there wasn't Internet.
I use command as
uqmi -d /dev/cdc-wdm0 --get-signal-info
to verify that the SIM has joined to the provider's network.
I found the image of fachos user (https://mega.nz/folder/tj5yTTgb#FzUuQNF4XaPqB--pnzxFIA) and it works but, sorry, I prefer the official images,
so I went back on the official image, with uqmi package and patch but still no Internet.
After two days, I gave up and use the uqmi package modified by mrhaav user (https://github.com/mrhaav/openwrt/tree/master/21.02.2 - TL-MR6400 v4 - LTE modem for WAN connection - #13 by Dotlee)
and it just works (and I would like to know the reason, but I didn't have time).
I found also a script for LTE led signal that is very useful (TP-Link TL-MR6400 v5.2 LTE configuration - #6 by suchagoodguy)
so, I closed everything and put "in production" this router/modem.
It seemed to work but
second problem: connect but no Internet after six hours.
After six hours with SIM connect and Internet working,
again the problem as indicate in the first problem section:
the SIM is joined to the LTE Network of the provider but no Internet.
It's always after six hours, I timed it.
I didn't find any informations about this in the log and I still have this problem.
I found a video on YouTube (https://www.youtube.com/watch?v=9vxJEZrR1Fk) where it showed the same problem but,
unfortunately it isn't in English, so I don't understand anything.
At the end of the video, there is a script to "auto-reconnect" the LTE module when the Internet is down....
it is just a ping to Google DNS and when there is an error, use the S&A algorithm: turn down/off and turn up/on LTE interface (in Italian: "Spegni&Accendi").
It's a crappy solution IMHO but I tried: unfortunately, in my case, the provider give an error when the SIM tries to connect again:
Error: Unknown error (DATA_FORMAT_FAILURE)
I need a quick solution because the router/modem it isn't near me (more then ~100Km) and I didn't a VPN (unfortunately the provider, Very Mobile, use a CG-NAT, so I have to install a server here and configure the router to connect automatically to the server),
so I use this command when the ping gives error:
Shame on me but it works but I don't like it.
I'll try with another SIM Very Mobile with a smartphone in hotspot if there are some problem after six hours,
to exclude a provider "problem" (or block) but I think it's a some fault in the package for the LTE module.
I use also "adblock" and "https-dns-proxy" modules but I use them also in another router and I don't have this problem.
Have a nice day.
Ps.: the script on the video on YouTube, I wrote down:
#https://www.youtube.com/watch?v=9vxJEZrR1Fk #!/bin/sh iface="WANLTE" #which interface to bring up/down host='188.8.131.52' #what to ping ping -c 2 -W 15 "$host" > /dev/null if [ $? -eq 0 ]; then echo ok exit 0 else ifdown "$iface" $$ ifup "$iface" fi