More info in the link below. I had a lot of issues about MTN"s Fixed LTE and this answered a lot of them.
https://mybroadband.co.za/news/wireless/326973-mtn-fixed-lte-heres-why-you-need-an-approved-router.html
ZTE also makes LTE routers. They have a ZTE MF286 which is cat 6.
Networks do not lock you to their networks when you use their router. At least not that I know of.
Best way to find actual deals is to start shopping for the things you want now. Take note of the prices now and compare with black Friday. Last year I saw one of the online stores actually take the price of a TV up on Back Friday.
My experience was below acceptable. Too much buffering and stutter. I tested in different locations and never got anywhere near 10Mbps. The speeds I experienced on MTN made me fall in love with MTN although the love was short lived.
Basically the whole point of the post if anyone missed it was: "Why are some very compatible routers that clearly offer the same experience not approved"?
They do specify and I take responsibility for not inspecting the list. That is my point here: "Put it into my B315 router (Yes I know, I will get to that part later). " I just assumed my routers would be compatible, which they are. Just not "APPROVED".
So I ordered a sim from Supersonic, waited a few days for delivery only to find out that the agent who handled my order used my home address as the delivery address instead of the address I explicitly specified! Had to wait a few more days for delivery from RAM.
I finally received the sim card...