said by daniel_n :Do you recommend installing a high quality splitter instead of the currently installed one by Comcast?
Generally, Comcast uses high-quality splitters, so unless there's some problem with it, the issue may be in your cabling or connections (though you say your downstream signal levels and SNRs are OK).
So if not that, then it may be an issue with your drop or the tap off of Comcast's line.
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[Connectivity] High Upstream power, T3 timeouts, Disconnects