Poor signal when close to the sure signal

[Smdvelo]

Even when using an extended Ethernet cable to move the Sure Signal into a room 20ft away from the router (but closer direct through the walls) the call quality on my iPhone is rubbish. 2 levels down in my lounge where previously I had no signal it works well and I have good coverage.
The SS has ruined what was previously a great signal on the top floor of the house in my office where the router is but has improved the signal where I previously didn't have one. Unplug the SS and the reverse happens.
Any suggestions?

[Retired-Lee]

Hi there Smdvelo,

Bizarre!

Could you give me your Sure Signal serial number please?

Thanks,

LeeH

[Smdvelo]

40124219755, why do you ask?