Hello Matt,
according to the IR829 datasheet the hardware supports dual LTE modems with possible fallover to 3G when needed.
https://www.cisco.com/c/en/us/products/collateral/routers/829-industrial-router/datasheet-c78-734981.html?dtid=osscdc000283
IR829M-2LTE-EA-*K9: This router includes integrated dual active LTE, a dual Wi-Fi, an mSATA SSD storage option, PoE-enabled Ethernet ports, SFP, and serial. Customers gain dual active LTE connectivity for WAN redundancy and load balancing features, with each modem supporting multimode 4G/3G for carriers operating in FDD LTE 2100 MHz (band 1), 1900 MHz (band 2, band 25), 1800 MHz (band 3), 1700 MHz (band 4), 850 MHz (band 5, band 26), 2600 MHz (band 7), 700 MHz (band 12, band 13, band 29), 800 MHz (band 20), 1900 MHz (band 25), 850 MHz (band 26), 700 MHz (band 29), and TDD LTE 2500 MHz (band 41). This product is backward-compatible, with WCDMA 2100 MHz (band 1), 1900 MHz (band 2), 1800 MHz (band 3), 1700 MHz (band 4), 850 MHz (band 5), and 900 MHz (band 8). It comes with dual 802.11n a/g/n 2.4 GHz and 5 GHz Wi-Fi radios. A field-replaceable mSATA SSD can be inserted into the mSATA SSD storage slot to add storage to the IR829M model.
So my understanding is that 5G is not supported, however 5G introduction will be gradual and support for 4G will not be dismissed. Depending on the geographical area your router can have 4G service or even it needs to fall back to 3G service (several other forum members have reported this kind of scenario).
To be noted IoT applications are an area of application for IPv6 as the number of devices that can be connected is very high.
Hope to help
Giuseppe