This is my 1st unifi lite bill. No extra charges on installation, TM just running 5m length of fibre to my house.

Right, Exactly that date of my unifi was installed without prorated.

Depends on where you use the most... if you got a small room downstairs with a mini office then put downstairs.. but if your pc mainly used in a room then perhaps upstairs....

I always put downstairs anyway....

Speed will depend on where u downloading from?

i'd assume that u're referring to the WAN (internet) IP address and not your internal network IP address... no it is not normal - shouldn't change every few minutes

abnormal

PPPoE is the right setting. The IP will change but it should be days weeks before it changes so definitely something is not right.

I had a similar prob earlier this year. My symptoms were:
- Internet will be non-responsive then...
- Router disconnects and reconnects to unifi
- IP address changes after reconnect
- Happens at certain times of the day (for me mostly evenings but quite unpredictable, morning/afternoon also got)
- It'll dis/reconnect like 20 times in 10 minutes
- It'll do that then it'll be ok for a few hours and then start again
- Phone line still works OK when the above problem occurs

In my case, it wasn't the modem or the router. Still using the same devices. Made a report to TM. No-one from TM came to check so I assume TM did something on their side. On the 2nd or 3rd week, everything was back to normal up to now.

Can you check your router logs for PPPoE disconnection? In my report to TM, I sent them my router logs where (after I turn on PPPoE debug), I can see keepalive packets from TM every 20 secs. Then it stops and disconnects.

It looks something like this during normal operation. I can't seem to find the screenshot I did for TM anymore.

What router are you using? Mine's a Mikrotik so the log will look different from yours. What options do you have for connection type? PPPoE can be used for both dynamic or fixed IP.

Connection Type: PPPoE is correct for the C1200.