My pennyworth on a new router ...
I find the BrightBox an excellent router, good features, reliable, fast N wireless, holds a fast connection ... Unless it is faulty, and there is no evidence that it is, there is no need to replace it and if it is faulty EE should replace it.
You can confirm its readings, more or less, by connecting the Siemens, which is a reasonable average router, for a bit.
It's always worth having a back-up router and the Siemens would do for that. Or I'd recommend looking for a
new Netgear DG834GT, but only G wireless, on eBay for under £20. No need to spend much on a router.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC