We have had an issue with our fibre to the box and copper to the house Internet connection, being dropped by my router and disconnecting intermittently from broadband and a weak phone line.
It took two phone calls and two visits from BT Openreach ™ before the problem was found at the top of the telegraph pole.

Hello, I've literally just finished working on your line, the fault was up the top of the pole and you have the local squirrels 🐿️ to thank for your problems, they like to hone their teeth on the telephone cables! I've repaired it and reset the service, you've gone from a faulty 44mbs to a stable 65mbs, should be a much improved service now.
What's more the connection is indeed stable!
Thanks to Duncan!