Wireless Joint

Hey everyone. Recently purchased a DualQ H721 V6 with a Quectal RM502-AE modem from what I presume is another user of this forum.

My connection works fantastically, I can access the internet easily. I use a tmobile plan, have it connected properly. The problem arises when I try to use it. After I start any kind of heavy usage (eg, I download a file larger than a few MB) my connection drops, requiring a restart of the modem to restore connection. Watch netflix, crash. Download a software update, crash. Zoom call, crash.

I have tried everything. I've flashed the firmware a dozen times (its currently running the latest goldenorb), I've fiddled with every setting I can think of. MBIM, QMI, all fail the same way. I can't think of what else could be going wrong - and I'm hoping one of you fine folks can help me.\

You may want to try upgrading the power supply. Check your system logs and modem connection logs and see if the modem is resetting. If the modem is resetting, which is what it sounds like is happening, then you may have a power delivery issue when the modem is under load.

Definitely not the power supply, hooked it up to a 4A charger and its still doing the same thing. Dead under load.

I bet it is still power related. Any way you can try the modem in another device?

Here are a few questions I would ask in troubleshooting:
- What antennas are you using?
- Do they all have separate ground plane or do any use a common ground plane?
- Are the antennas connected to earth ground?
- Is the power supply or router connected to earth ground?
- Does your residence have old electrical wiring that may have potential poor grounding?
- Unhook all but 1 antenna. Does the modem still drop under load?

These newer modems suck the power when at full throttle. I've also seen where a floating ground or poorly connected earth ground has effected dropouts and random disconnects. Honestly, I question many of the older devices out there on the market and whether they are adequate enough to supply enough power to these newer power hungry modems. Best bet is to go with the usb3/m.2 adapter from this site that allows a secondary power source to help with the extra power. The newest model is best as it disconnects the secondary power source when the primary source disconnects. Using older versions or just using a usb splitter cable can backfeed power back through the entire usb power circuit and also won't let you completely kill power to the modem or device.

Antennas are Cisco LTE-ANTM-SMA-D, I just bought a WG1608 thinking it was the router itself as I had read online the 721s could be difficult, still in the same boat.

Antennas aren't earth grounded, they're currently screwed into the back of the 1608. I've got a wifix 4×4 mimo enclosure inbound, I think my signal strength might be what is doing it. I can't test with 1 antenna, I don't get enough signal strength to make a connection. At best my signal strength is in the high 50s and have a not great RSCP (-100 dBm) and RSSI (-73).

If the antenna fails, I'll try the m.2 enclosure next. Thanks for the help!