For various reasons I switched to a $15/month static WAN IP a couple of months ago on Spark Wireless 4g / LTE.

I'm based in rural North Canterbury, and before the switch I'd get Speedtest results 100Mbs outside of high demand times i.e. 11.00pm to 7.00am, and around 60 to 70 Mbs at other times via Spark's Christchurch server.... which was pretty good, although the Spark mast is only about 1km away with a clear line of site across open fields so perhaps not surprising.

Now however, Speedtest defaults to servers in Auckland or Wellington, with much slower speeds around 20 to 30 Mbps no matter what time of day. And when I select Spark Christchurch as the test server, it's even slower with higher latency.

Can I ask whether this is normal with static WAN IPs, and is there anything I can do to improve things?

The system is: Spark Smart Modem 2 reduced to modem only functionality + NAT + firewall, feeding an EdgeRouter 4 via the SSM2 DMZ. Self hosted UniFi Network Server 8.4.59. Various UniFi switches and WAPs. Default main LAN and various VLANs. Cat 6 reticulation to all fixed equipment.