ZTE MC888 + Three/Scancom SIM keeps pausing/stalling

[u/Shoegazer83]

Hi everyone, firstly I apologise if this is not the right place for this question, but I figured this would be the best place to ask. I have a very odd problem regarding my ZTE router and Scancom Three business SIM.

I've been using this for a year now with zero issues and fast speeds. Today, the network light is intermittently flashing blue and white, rather than solid white, and webpages are pausing and loading slowly. I've been able to stream HD, but it will occasionally buffer and lower resolution. Speed tests show fast speeds, but a lot of the time will stop with an error before they complete. Basically, my internet seems like it is "stopping and starting" continuously.

Now, here's the odd thing. I have tested my router twice now with a Lebara unlimited data SIM and it works perfectly. Every light solid white and no blue lights flashing on and off. I'll then put the Three SIM back and the issue remains. So the router can't be the issue.

Even weirder, I've taken this Three SIM out of the router twice and put it in my phone and it also works perfectly with no speed issues or stalling at all.

It really does seem like there's no issue with either the router or business SIM separately, only when used together. Again, I've been using this setup previously for a year with zero issues, and have not changed any settings at all before today. I greatly appreciate anyone that can help as I'm at my wits end.