To begin I don't know what the person who appeared after the chat bot, her name was "Laura" told me that support on 020 690 400 is available on a Sunday when it is only for PUK codes and TV service failure.
Anyway I ordered a Telia 4G data SIM to use in a mokkula that I already own, a Huawei E3372 with HiLink firmware. I placed the device into a PC to compare the speeds using both the DNA and Telia 4G data SIM cards.
I tried the speedtest plugin in the Telia site at https://www.telia.fi/kauppa/kodin-netti/tee-nopeustesti
Some example up/down speeds below with example test links. I don't think this is a mokkula settings or firmware issue?
Telia - 8.5/ 2.6/ and 6.9/ 2.5/ (mbps)
DNA - 55/ 30/ and 47/ 36/ (mbps)