My wireless range appears to be reducing as there are a number of rooms in the house where there is no signal. The issue appears to be gradually getting worse. I assume a replacement is the only solution?
a replacement what? - if you have the SH1 then a replacement is long overdue - a call to retentions should get you said replacement for free or at worst postage - dont get too involved just say the wifi is rubbish which it is
other models of the SH are all about as good or bad as each other so replacing one of those will likely do nothing - degrading of the wifi over time is usually due to other wifi routers around you - wifi can also be degraded by things such as chordless phone - microwaves and a host of other things
so first make sure your wifi is using a channel that is not busy from other wifi signals - download inSSIDer for a pc or similar on a mobile device and set your channel to the least busy - that should help
all the SH's are get you going devices on wifi and if wifi is important to you then the only real answer is SH in modem mode with a good 3rd party router
We do have a number of devices, 4 phones, 4 laptops and 4 iPads but there are only 6-7 devices attached at any one time. The issue is getting worse and until 6 months ago there was no issue and it has gradually got worse.