Synology maintains a compatibility database: https://www.synology.com/de-de...
There it is mentioned that from firmware 1.4 onwards this device no longer supports any 3G/4G dongles ("EOL - End Of Life". I would therefore not recommend using a USB stick for internet access to the MR2200ac, but a device with an Ethernet connection.

I can't help you there. I use it for a multimedia Android moniciver in the car, where it works well.