Nothing wrong with patching up to get it working again as a temporary measure but don't expect it to last very long.
If you are going to lay in new cable, armoured cable would be the most robust solution if you are going to lay it in the drain channel again (but also the most expensive). You would need some CW (= external grade) cable glands to terminate the armouring (if there is any risk of moisture at the ends) into boxes where you would fit a Cat 6 faceplate at each end. The armoured cable is weather and waterproof. The steel wire armour protects the cable from mechanical damage/crushing and from being nibbled by rodents.
Cheaper option is to use external grade Cat 6 (without the SWA) and put the cable inside a conduit of some kind. Hose pipe is not ideal as it is not designed to pull cables through (it will be hard to pull the cables over a long run) and it can be crushed easily. Seek out a corrugated flexible electrical conduit or a duct which is designed to be used outdoors (UV resistant and waterproof). A proper electrical duct will allow the cable to be pulled through more easily. Ideally run the conduit in one continuous pieces to prevent water ingress.
Ideal Yellow 77 can be used to help pull cables through long runs.
https://www.toolstation.com/ideal-industries-yellow-77-wire-cable-pulling-lubricant/p67429
Good trick below to allow you to get a pull string through a long piece of conduit
https://www.youtube.com/watch?v=ldgF_Q2T19A
Corrugated flexible cable conduit will resist crushing but won't be rodent-proof.
Use a proper punch down tool. The plastic ones rarely ever push the cable far enough into the connector to pierce the cable insulation, resulting in unreliable connections. A proper punch down tool will crop the little strands of wire from the connector.
It is possible to use all sorts of kit to run in an outdoor connection but, if you want it to be reliable and last any length of time (against your outlay of hard-earned cash), you need to use the correct tools and materials.
