Never had a good experience with Speedify, never worked as advertised.
Later, I tried bonding for speed in other countries and it always was slower or the same as one connection.
You are better off with a Peplink device and their SpeedFusion service. At least you can host it yourself in cloud providers and control how much bandwidth it gets.
Edit: I have one of these: https://www.peplinkworks.com/max-transit-duo.asp
Appreciate the link, but half the page is "get a quote"
You can find cheaper models if you only have 1 LTE WAN + 1 ethernet WAN.
I also have a Nighthawk M2 which is an LTE "router" with a battery that has an ethernet port. At one point I had that plugged into the ethernet WAN port so I had 3 LTE modems going at the same time. This is obviously beneficial when there are multiple carriers in the area with their own infrastructure.
We now default to a mode that uses up to 8 TCP connections in parallel on each internet connection to let us reach the full speed of connections even if they have latency and loss that limits the performance of TCP.
We'd love to get you to try it again. Email us at support@speedify.com and we'd get you a license to reevaluate.
Unfortunately the cheapest models are at least few hundreds $ and reliable dedicated servers aren't cheap.
It seems they suffer from a fundamental network quality issue. If I had access to a single network with enough quality, I'd just use it. Every time I've needed Speedify, all of the connection options have been terrible. It can only help so much when you're pooling a hotel sharing 100MB connection and two phones with 1 bar.
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I did find their billing a bit shady. They force you to go to your payment provider to cancel the subscription.