As I have a shitty asymmetric DSL connection (5,6 Mbps down; 0,9 Mbps up), I tried to implement some bufferbloat mitigation with the Traffic Limiter and the fq_codel scheduler, as stated here.
The problem with this method is that the rule is applied on the LAN interface. I want it to be applied on the WAN interface, as I have a second WAN interface with an LTE connection in failover, with totally different bandwidths.

This is what I have done:

• I created two limiters, "download" and "upload", set at 95 % of the max bandwidth.

• I created the queues "out" and "in", respectively for the limiters "upload" and "download", without any mask.

• I created a Floating Rule with settings linked on images below.

https://imgur.com/UTuR9RK
https://imgur.com/iOmLCq2
https://imgur.com/CgOd85I

When the rule is applied on LAN, bufferbloat is really mitigated, and I get an A on dslreports test.
When the rule is applied on my WAN via a floating rule, this happens depending of the in/out settings I changed:

• nothing is mitigated;

• upload is completely broken and blocked;

• download speeds are at upload speeds.

I don't know what to do. I need your help guys.