[FS#762] TP-Link WR1043ND v4: Network on switch fails at random

[LEDE Bugs]

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FS#762 - TP-Link WR1043ND v4: Network on switch fails at random
User who did this - Mihnea (TVTVTV)

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Hello guys, i have just purchased one 1043ND v4 in Romania. ISP is RDS, bandwidth is 300/150 mbit. My unit is also 100% affected by this bug and i can reproduce it in a very reliable fashion. All i have to do is load my ISP's [[http://www.rcs-rds.ro/internet-digi-net/testeaza-ti-viteza|speedtest page]] and run a test. The D/L part of the test is always a pass, but whenever the U/L test comes up, the router's copper ports freeze completely (WAN, LAN). The heartbeat LED continues to "beat", i can see my Samba share no issues, wireless works (but no internet - i can access LuCi though from any device connected to the Wi-Fi network) but WAN loses connection and my desktop PC (only device connected to the router via wire) "sees" the connection as "Identifying...". The status LEDs for both WAN and LAN continue to work as intended, as if i remove the cable from either LAN 1 or WAN, the corresponding LEDs turn off. Inserting the cable again presents a green LED.

I have had this issue happen in two other contexts: downloading a large file over Torrent at ~30 MB/s and switching QoS on in LuCi while a 15 MB/s download was running.

Attempts to fix:

1) Enabling QOS and limiting the upload to 140 mbit: this works perfectly, i can no longer "crash" the router via the speedtest page. The router still crashes under HEAVY download traffic (~300 mbit, wired). Fix fail;

2) Reverting to stock firmware (via TFTP). This fixes the problem 100% - the router no longer hangs in either one of the two above scenarios at all. "Fix" works.

My conclusion is, then, that this is an issue with Lede. Please let me know what you guys need me to do (capture logs etc.) and i will gladly help.

3'rd party FWs tested: SuperWRT r5275 (https://superwrt.download/), Lede 17.01.4.

I have attached two screenshots, one of a failed test that locks up the router and a successful one using the stock FW.

Have a nice evening! :)
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=762#comment3828