I think QOS will help ALOT with lower speed connections. At the very least, it will throttle bandwidth to all users in a fair manner so every application gets some bandwidth, which will cause many applications like youtube or netflix to lower resolution. I've tested this, and FQ_CODEL and CAKE both work very well to applying bandwidth throttling. It especially helps with other users on the network that are streaming video because you set the limits to about 85-90% of your bandwidth. It throttles them down to lets say 90% of your bandwidth that you set, giving 10% of headroom for new traffic spikes in your game packets. Or if another user jumps on the network, that 10% headroom allows the algorithm time to throttle the other users on the network down without crippling the network.
The FQ_Codel and CAKE algorithms help a ton. I use cake at my house, and my network has been rock solid. For the friends with routers that support DDWRT or AsusMerlinOPENWRT, I've upgraded their routers and turn on FQ_CODEL for them. Their networks are excellent. I've done testing at their homes and the algorithms do live up to the hype. The worst internet connection in my area is 25mbps DSL, which a single coworker has. I put Merlin on their ASUS router and turned on FQ_CODEL. Doing a full bandwidth test with 2 HD streams and 2 gaming devices(laptop and console). I set his bandwidth for 20mbps because his network can sometimes dip to 21mbps during speed tests. We made sure the console was running a gaming library update while we gamed on the laptop. Everything ran smoothly no lag, except for when a new app is launched and streaming starts, but it quickly goes away. The network was fully saturated and the FQ_CODEL brought all usage down to 20mbps. When a new client jumps on the network, the algorithm works to throttle the other clients to make room for the new client, it's not instant but fairly quick. Once the video streams settle down, the network is lag free.
We turned QOS off and tried the factory QOS options. In either case, the video streams would buffer and the game console update speed would fluctuate alot. The gaming on the laptop was lag city. The bandwidth was a free for all with seemingly no rhyme or reason to who got however much bandwidth. It relied on youtube and netflix to lower resolution themselves before the network was usable but the video would still occasionally buffer. Gaming was still laggy.
I haven't used this algorithm at the super low speeds likes yours. But it seems that the minimum speed for FQ_CODEL to work is 2.4mbps due to the 5ms target duration.
https://bloat.bufferbloat.narkive.c...ore-best-practices-for-slow-connections-1mbit With such a low connection, you'll still probably have lag, but at least with advanced QOS algorithms, you'll get the most out of what you do have, and lag will be reduced.
The problem is, these algorithms use alot of cpu power. Even the best ARM routers max out at about 300-400mbps running these algorithms. You have to switch to an x86 router if you have higher internet speeds. For the OP, I would get a router with a half decent CPU. If you can load DDWRT or OPENWRT on it, you can get all the latest algorithms such as CAKE. Asus Merlin has FQ_CODEL on it, which in itself works well too.