Welcome to the Community and thanks for posting on the Forum. I'm sorry to hear that your BBC iPlayer via the TiVo® isn't usable.
I have been able to access your account via your Forum details and run remote testing to your TiVo®. The good news is that all the signals and levels in your TiVo® are spot on, however, I can see that there is a high demand issue in your area, which is causing the iPlayer problem.
Details on this:
Tivo/Youtube buffering - You might find that at certain times of the day some programmes from your TiVo BBC player service are buffering or freezing.
We are planning to undertake some upgrades to support the increased demand for our services in your area. When completed, any buffering on TiVo® apps you may be experiencing (particularly at peak times such as evenings and weekends) will be resolved.
Currently, there is no estimated resolution time for this. Apologies for any inconvenience this may cause.
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