Question about ASUS 4g-Ac68u

Hoi,

1: Yes, it works with Salt, you just have to make an adjustment in the settings. APN -> Internet. I have been using this setup since last year :)
Unfortunately, the device only has 1 sim card slot...

2: do you mean e.g. 2 providers on the same router? This is possible via Dual WAN, e.g. you can then run Salt and another provider at the same time. But here only 1x via SIM and 1x via WAN port.