I've found myself in a similar situation. What I've learnt is that good load-balancing makes a surprising difference. It won't help you back up your files to the cloud any faster, but it will keep your Internet connection usable for other people while you do so. I've gone from being unable to hold one decent Skype conversation to being able to hold two in parallel on the same network. I've gone from ping times of up to 800ms when my wife used WhatsApp to ping times below 25ms in all realistic load conditions, including WhatsApp, and even flat-out file transfers in both directions at once. For video conferencing and general Web browsing, low latency is usually more important than high bandwidth.
The route I took was to place a small, low-power Linux box between my network and my ADSL router, running OpenWRT, and then configure load-balancing on that. A Web search for "bufferbloat cake" (no, really :-)) will show you one of the most useful Web sites I found.
One other measure you can take is aggressive content-blocking. I use Pi-Hole, uBlock Origin, Privacy Badger and Blokada, and I recommend them all. If you don't have much bandwidth, you don't want to give half of it away to marketers and creepy trackers. Use what little you have to work for you, rather than against you.
Having started from a position of knowing very little about Linux networking, I'd say that the Linux networking stack is powerful, flexible and fast, but it's let down by the available documentation, most of which seems to have been written at least fifteen years ago, and much of which is simply out-of-date. I couldn't find anything that just starts at the beginning and tells you everything you want to know, and is based on modern Linux commands and facilities. I'd write it myself if I understood it well enough but, honestly, I still don't. For anyone who wants to contribute to Linux but is a wordsmith rather than a coder, here's your chance.
I'm sorry -- slip of the keyboard. Where I wrote "load-balancing" here yesterday (not once but twice), I should have written "traffic-shaping." I have only one Internet connection -- that's all I can get here -- but traffic-shaping moves the queue from the ADSL router or the ISP into the little Linux box, where it can be managed better, and ensures that heavy users such as big uploads and downloads don't crowd out interactive users. The Web search I suggested will make more sense in that context!
The route I took was to place a small, low-power Linux box between my network and my ADSL router, running OpenWRT, and then configure load-balancing on that. A Web search for "bufferbloat cake" (no, really :-)) will show you one of the most useful Web sites I found.
One other measure you can take is aggressive content-blocking. I use Pi-Hole, uBlock Origin, Privacy Badger and Blokada, and I recommend them all. If you don't have much bandwidth, you don't want to give half of it away to marketers and creepy trackers. Use what little you have to work for you, rather than against you.
Having started from a position of knowing very little about Linux networking, I'd say that the Linux networking stack is powerful, flexible and fast, but it's let down by the available documentation, most of which seems to have been written at least fifteen years ago, and much of which is simply out-of-date. I couldn't find anything that just starts at the beginning and tells you everything you want to know, and is based on modern Linux commands and facilities. I'd write it myself if I understood it well enough but, honestly, I still don't. For anyone who wants to contribute to Linux but is a wordsmith rather than a coder, here's your chance.