Resume from Suspend issues with Surf SOHO + 754S usb hotspot modem

Replaced my dead usb stick modem with a 754S but it’s not successfully coming back from being put in disabled mode (lower power consumption). Keeping it at full power is not a solution - modem would probably die quickly but even so I don’t want it that way

I found that if I unplug and replug the hotspot, then when it comes back up it works, but obviously that’s not a good solution as the whole point of the Surfo SOHO’s fallback mechanism is for automatic, unattended transfer from a failing primary WAN to backup.

So my question is, is there any way to have the Surfo SOHO automatically power off the usb modem completely before powering it back on instead of putting it into sleep mode? Somehow it gets wedged while sitting in sleep mode. (Note that I didn’t have this issue with the previous usb stick mode, at least before it suddenly died.)

What USB modem is generally considered the best choice for reliability with the Surf SOHO, taking into account that we’ll lose 3G on most networks by 2022 if not already, so I’d prefer a newer-ish product. (754S is from 2012 but it support 4G LTE.)

What I’m not getting is that the automatic “safety check” run by the Surf SOHO reports OK while the modem is not responding, so I’m wondering whether it’s broken in some weird way that prevents the Surf SOHO from serving web requests from my PC while passing the safety checks and internal pings from the admin page.