T3/T4 timeouts are usually cause by noise on the upstream channel.
Your downstream signal levels are slightly on the high side with good SNR. But you are getting some errors which would be indicative of random noise. Upstream power levels are on the low side (indicating minimum signal loss).
I would suggest you follow the cable line from where it enters the premises, and find any/all connectors. Disconnect each and make sure it is clean, then reconnect. Also be sure there are no open connection points (e.g. 3-way splitter with only two cables connected). Finally, you could try adding a 6 dB attenuator in front of the modem to bring down the signal levels.