Fibre has higher ping than ADSL?

When I upgraded to a fibre service, I was hoping that my latency would be quite a bit lower as I frequently play latency-specific online games. While this isn't really important, I'm wondering why my line's ping times have since increased from when fibre services were first activated.

When the line was first activated, ping times via a local speedtest.net server were about 12-14ms (compared to the previous 29-31ms through an ADSL-based service), and a ping to my ISP's DNS servers resulted in about 4ms (through command prompt).

A few weeks later, our line reconnected (at about 9AM), and since then the received Speedtest results are now showing a ping of about 32-35ms, and 11ms to my local ISP's DNS.

Are there any known reasons as to why has this change happened to my line, and is there any way of somehow lowering this latency?

Here are the stats from my router/modem (forgive me, I've only got limited stats on this DSL-3782)

UpLink / DownLink
SNR Margin: 13.0 dB / 5.5 dB
Line Attenuation: 7.7 dB / 22.2 dB
Output Power: 6.9 dbm / 10.0 dbm
Data Rate: 2000 kbps / 23420 kbps
ES: 7 / 473
SES: 0 / 18
UAS: 50 / 50
FEC: 229 / 33220901
CRC: 7 / 1761

Thanks!

What modem are you using?

It's possible some level of interleaving has been applied.

I've only got limited stats on this DSL-3782

Definitely interleaving

7ms due to interleaving would not totally account for a dump of 15ms so while interleaving looks to have raised latency something else in the ISP network or elsewhere has changed too