Arrived onsite and was told about the issue at hand. Immediately from the age of the home i knew it was one of a few possibilities, so i walked the resident through the things i was going to look at, and he came with me for my inspection. He showed us an outlet under the stairs that had lost power, that his wifi derived from. He told me that went out when the outside Christmas lights went out. I asked to see the unfinished areas/utility rooms in the basement and explained i was looking for the house GFCI, that would be controlling those outlets. I found it in the same room as the furnace, tripped after a rainstorm. I went to all the outside outlets and did a visual inspection and the front one was fine, but the side and back one had broken w/p tabs inside and the in use cover seals were so degraded that not only did water get in but both covers had a thick layer of green growing in them. I talked to the resident about replacing the WR outlet and in use covers had a for those two locati