Advice regarding cellular modem

[tx48]

Hi,

I have recently replaced my ISP-supplied router with OPNsense running in a Proxmox VM on an HP T730 Thin Client. It's working really well so far and is a big improvement!

It's currently on a DSL line, but I'd like to experiment with mobile connectivity (AKA cellular for those in the US  . I've been researching a suitable modem and antenna, but the information available is quite fragmented and I'm having some trouble settling on the right choice. I'm doing more research, but thought I'd ask on here as well.

The HP T730 does have an M.2 slot that's intended for an HP-supplied Wi-Fi/Bluetooth module, so I could possibly find an M.2 cellular modem that's compatible with this slot and OPNsense, but I'm thinking a USB device might be more straightforward (it has several external USB ports). My first question: am I right in thinking a USB modem is probably the better/easier way to go?

I have a 4-port NIC in the T730 with only 1 port currently used, so Ethernet-based modems are also an option.

I'd like to get some advice on what might be a good modem to go for. Hopefully the below gives you the information needed:

• I am running the latest build of OPNsense.
• The M.2 slot is 2230 form factor and E-keyed (in case you want to recommend an M.2 option).
• I am in the UK. I'm not sure which mobile carrier I'll use (planning to experiment to find which gives me the best experience). I've only just started educating myself about 4G/5G bands, but I believe the most important bands for 4G/LTE in the UK are 3, 7 and 20 and n78 for 5G NR.
• For future-proofing, it would be nice if the modem supported 5G, but not essential (4G/LTE is fine).

Thanks in advance!