And then I did a ping from the phone to that PC 192.168.150.253 which added the phone MAC address to the PC arp table, and the PC was able to reach out to the phone after and ssh worked from PC to phone.
Interesting, I have the same behaviour on my jolla, and I blame powersaving settings in the wireless card/driver. I never got time to troubleshoot it in details though.
If that is the only problem then you could try adding a static ARP entry on your PC.
That certainly sounds like a plausible line of investigation.
Fairly obviously a device where power consumption is critical and time on standby is an important attribute, operating as a server is not ideal, and may not be compatible with the current implementation.
Would need to look at selected powersave mode, state of the device on the host (i.e. on the phone itself c.f. the WiFi card) and technically at your wireless access point settings (defaults will very likely be fine but if you have set something weird …) and associations.
I note that I can’t ping my existing spyphone from my PC when the phone is asleep.
This is using a VM and not the actual phone, so your mileage may vary, but I can confirm that simply running sudo systemctl start ssh like kop316 said and then sshing in from a PC worked for me.
that eventually was my quick and dirty workaround where i just hardcoded static arp entry and short dns alias to ssh to the phone from development laptop (to push/debug apps). And as there’s nothing more permanent than temporary that’s how it still is