OK so without any obstructions, 25m is well within range of an access point, even more so for a centrally placed one if never more than 15m away.
Sounds more likely to do with materials in dividing walls, such as a thicker supporting wall and/or the properties of some insulation materials.
Kitchens and bathrooms may also have more metal in their construction (e.g. water tanks, boilers) or appliances.
Depending on layout 2 access points ought to be sufficient spaced 8-10m apart - if you can take advantage of a connecting hallway or other circulation space to reduce the number of walls between most devices and their nearest AP. Unfortunately the study isn't the best place for the first AP if it is at one end of the property.
In home setups aesthetics takes precedence over technology compared with office spaces, understandably so.
It's also why I mentioned loft spaces and ceiling mounting as that would enable you to have hidden cabling between study network and APs, and to use the disc APs with a flattened doughnut pattern which probably suits a bungalow layout not needing much vertical propagation.
If you have an Android smartphone or tablet you can install one of the many free Wi-Fi visual apps (UniFi has one) and walk from room to room to see where the biggest drops in signal occur. Similar programs also available for laptops - you don't need to pay for a commercial survey tool either.
(Even though devices can detect an AP and hold a connection at the bottom end of sensitivity say -90 to -96dBm)
If your received signal drops below -70dBm it's becoming marginal - things like email, social media and background apps will still update but streaming, TVs, audio/video chat and other real-time services are more likely to notice it.
For 802.11ac and faster, -60dBm or better throughout is preferred.
On a networking point as you already have a very capable pfSense router, you don't necessarily need more routers, only access points, which just take care of attaching Wi-Fi devices to the underlying wired network rather than other responsibilities such as DHCP, DNS, routing, firewalling, NAT and Internet, likely all handled on the pfSense box.
prlzx on iDNET: FTTC (VDSL) at ~40Mbps / 10Mbps
with IP4/6 (no v6? - not true Internet)
Edited by prlzx (Sat 20-Jun-20 16:18:24)