Old house with stone walls that is a long rectangle. Want to use WiFi to reach an Arlo camera outside garage which would mean the nest point has to “pass” through a metal house door and an aluminum garage door. The signal is so weak and works intermittently. Would this more likely work with adding another point? Thank you!
Ouch. Stone and metal materials significantly degrade WiFi signals. I would not expect throwing more Nest WiFi Point at the problem would solve the problem (I mean, it might, but it's unlikely). In an environment like that, we need to use wires to get across some of those barriers rather than trying to use more WiFi. I would try to build a wired backbone to connect multiple Google WiFi units back to a primary Nest WiFi Router (assuming that's what you already have) and place those Google WiFi units in locations that can provide coverage to the clients you care most about. If possible, putting one in the garage may provide the coverage our Arlo camera needs, though it really depends on the material the garage walls are made from. If it's also stone, then it's going to be a challenge, and you may need to look into externally-mounted access point solutions (which Google doesn't make).
P.S. The reason I am recommending Google WiFi units is because they are compatible with Nest WiFi systems, have Ethernet ports that can be used to connect back to the primary Nest WiFi Router, and are significantly less expensive than buying more Nest WiFi Router units to use as wired secondaries.
I just wanted to jump in real fast to see if you saw MichaelP's reply and to see if you still needed some help on this or if you were able to get it sorted out. If you are still needing some help, just let us know and we'll be happy to continue helping.