Outdoor tv aerial not working downstairs

Have you looked around the entrance of the wire. I.e. if it's coming from outside, have you checked the jumper to see if its frayed at all?

the problem is water. you need to determine where the water comes from, eliminate the water leakage, dry the installations and it will work as it should

Hai,I think it’s cable need to replace ,condensation catch from the splitter area, need find where is the main cable .

Check in loft to make sure connection box ok could be socket make sure all leads are dry and not frayed anywhere in

Might need a new connection to the aerial from that tv

Because the digital signal is effectively weaker than the old analogue system it either needs a booster/ splitter to run two TVs or an aerial per TV. Also the cable used, whilst still being coax,is double shielded. I also recommend not to have joins in the cable . You also need to check that none of the shielding is touching the central wire anywhere as this will ruin your signal.I would take the opportunity to replace the cable with the correct double shielded coax as it will improve reception.

The cable is damaged and is got water siping inside it needs a new cable

Although I'm not a TV engineer the problem is a weak signal caused by weak ingress disassemble connections dry of and re assemble if ok try to illiminate water ingress.