Best data-only sim for 4G router

MeadowsVale

I've recently purchased a Cudy LT300 4G router from Amazon for backup purposes.

Here's the problem - I acquired a sim card from Smarty and purchased the £20/month unlimited data-only plan but the speeds are so diabolical. Lucky to get more than 2Mbps down on a good day which makes it unusable for most things. I actually feel like I've been ripped off paying Smarty £20 for this.

I then decided to take my Lebara sim out of my car to test and see if that improved things, well slightly, I now get max 15Mbps down but still nothing to write home about.

Any recommendations for a data sim that actually comes true to their promises? or is it all just a swizz promising big numbers while failing to deliver?

I'm not too fussed over which network as they all have good coverage here.

Woodstok2000

EE/3 are both pretty good but it can vary hugely depending on coverage, distance from mast etc. Could you borrow a few sims off people and test them out?

flaneurs_lobster

MeadowsVale said:

I'm not too fussed over which network as they all have good coverage here.

How are you making that observation? If it's the coverage maps that the networks publish then they are pretty meaningless when you get to the individual dwelling granularity. Local geography, buildings, trees and the construction materials of your house will all be factors in how good any mobile signal is.

Have you tried that 4G router closer to windows, different sides of the house, or higher up?

What's the signal like on your phone? Who's the carrier?

That Cudy only uses the 2.4GHz Wi-Fi band which is slower than the 5GHZ of other routers, but it can still support speeds far higher than you are seeing.

Frozen_up_north

I have a couple of TP-Link Archer NX200 5G routers, one at a second home. Both use EE data SIMs from Scancom (via Amazon).
I have just run a speed test from my iPhone (WiFi connection to the router, about 8 feet away). Speed is 82.4 Mb/s down, 7.45 Mb/s up, 7 mS jitter.
This particular router is about half a mile from the EE mast, it shows a 5G connection to the site, which is through 2 brick walls and several nearby houses in the direction of the mast.
The local EE site is not true 5G, it’s a 5G radio connected to a “4G” backplane, or whatever the expression is. Closer to the site my iPhone gets greater than 200 Mb/s down.

Keep_pedalling

Smarty use Three’s network so don’t expect any improvement if you try to use them or any of the other providers who use that network. 

Do you really need unlimited data for a back-up service?

huw01

I use Mozillion for my mobile plan. They don't throttle EE speeds. Worth having a look, they have some competitive plans. On 4G I get 71 download an 20 upload, that's plenty for me, when I get 5G it's really fast. I did a a test in Cardiff recently and it was 335 download and 70 upload. 
I have a backup PAYG sim with giffgaf in case of power cuts ( I loose the EE signal when there is a powercut at home as the mast is nearby and goes off as well ) and well giffgaff who use o2 is terrible. I can just about make a phone call

flaneurs_lobster

Probably worth a thread on it's own but Revolut are about to start a mobile service that will offer unlimited data for £12.50/mth (albeit limited to 100Mbps). Uses Vodafone network.

https://www.revolut.com/news/revolut_to_launch_mobile_plans_in_a_direct_challenge_to_traditional_network_providers/

Bit more independent thought here

https://www.ispreview.co.uk/index.php/2025/12/revolut-mobile-finally-starts-rolling-out-unlimited-5g-service-in-the-uk.html

muffinhead

Another thing to consider is that your router is only Cat 4, this means that it is unable to combine multiple network bands that would allow for increased speed.

At my home my Cat4 router on Three offered speeds of 25Mbps down and 10Mbps up. I upgraded to a Cat 19 device and got speeds of 300Mbps down and 50Mbps up. This was using the same sim card, network and router position on a 4G connection.

The choice of device (and its position) can have just as much bearing on the speeds as the network choice.

This website should help you with network choice for your location: https://bidb.uk/

and this one explains carrier aggregation in more detail:

https://4grouter.co.uk/4g-and-5g-lte-categories-and-their-characteristics-cat4-cat6-cat12-etc/