Product(s) recommendation for Home

I am looking for a solution to bond a slow DSL line with an LTE connection (via wifi, wired or USB).
The DSL tops out 3 Mbps and the LTE Hotspot is 5-20 Mps. The hotspot will be in the house most of the time, although it will be taken mobile from time to time. The hotspot has unlimited data. I may want to connect a second LTE source via iPhone hotspot if that possible. The current router is an Apple airport extreme b/g/n dual band. The devices that connect regularly are 2 laptops, 2 iPads, Sony smart TV, SONOS, directv genie, and Apple tv. The airplay is buffers forever and almost never plays video, the directv on demand download buffers constantly also. Looking for a production solution for 2016 sq feet single story house. Thank you for help in advance.

The Airplay buffering issue has nothing to do with your internet connection because this is using Layer 2 on your LAN segment only, so this could be a weak Wi-Fi or interference issue.

You could go with a Balance 20 or Balance One and tether the hotspot via USB and connect the DSL to an Ethernet WAN port. Then you can create outbound rules to force your bandwidth intensive devices to always use the LTE connection and other devices can go out the DSL.

Thank you for your recommendation.
If I wanted to add a second LTE connection via iPhone hotspot, would I need a Surf OTG and Balance 30, since that would be a total of 3 WANs (DSL, LTE via USB, and LTE via iPhone/SOTG) ?
Also does Peplink have any prodicts that incorporate MU-MIMO technology?

You could actually use a Balance 20 + a Surf OTG because the USB port is already a dedicated WAN.

I’m sure we will be coming out with a 4x4 product that supports MU-MIMO at some point down the road.