[FS#362] WR1043ND v4 Slow WAN -> LAN Whilst Synced @100Mbps

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - SpiderVice (Spider-Vice) 

Attached to Project - LEDE Project
Summary - WR1043ND v4 Slow WAN -> LAN Whilst Synced @100Mbps
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Medium
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Recently, builds for this device have started to be made, but there's a very peculiar issue I've found. Any client that is synced to 100 Mbps (and not 1 Gbps, in my case due to incapacity of the cable used) gets their speed seemingly throttled to 20-30 Mbps. My connection is a 100 Mbps connection, and I get full 95 Mbps (Hardware NAT disabled) on the stock firmware, and I also get this speed on LEDE __only if I use a 1 Gbps link__.

Speedtest on the stock firmware with the 100 Mbps link: http://www.speedtest.net/result/5904234776.png
Speedtest on the  latest LEDE with the 100 Mbps link: http://www.speedtest.net/result/5915271748.png
1 Gbps links get full speed, as expected.

If I perform a transfer from LAN to LAN, I get full speed on the 100 Mbps link. The resulting speed graph is not a hard-cap, but seemingly some kind of throttle/flow control being applied. I cannot change any settings with ethtool as it throws 'not supported' errors.

Only happens WAN > LAN connections.
Nothing of interest in the logs, unless I can somehow get a more verbose log of the connection status.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=362