Looks like an upstream noise issue to me (that beggars up the downstream channels, hence the slow download speeds). You can see that from the maxed out power on three of the upstream channels, and the T3 errors across all four upstream channels. The unwelcome downstream uncorrected (post-RS) errors are probably caused by individual channels dropping out.
I'll flag that for the forum staff to advise, and it'll probably need a technician to visit and fix that.
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