Using xFi Pods Gen 1 and 2?

I've had the 1st Gen xFi pods since 2018 and decided to upgrade and buy the new 2nd Gen xFi Pod. At first using it, it show a tremendous difference  compared to the 1st gen as it gave me up to 500 Mbps. Few months pass and now it drops to around max 150 Mbps. Does anyone know if using the 2nd Gen with the 1st Gen pods affects the performance? Also, anyone know where the best places to put them? I'm clueless lol