During our recent heatwave (still on-going), my DSL line would suddenly drop out, between 2pm and 3pm everyday so far. I was using the BT Openreach FTTC modem. So as soon as this would happen, the modem would need rebooting. Then after a few minutes, it would happen again. At least 4 times every day.
Now I thought this due to the FTTC modem over heating/faulty in this weather. So swapped for the Plusnet Hub One router just to be sure. (its sits in a well ventilated area) Today, I have had 6 drop outs starting from 2:30pm. Last one was at 3:50pm.