Flaky wifi is sometimes just due to a loose connection somewhere can you do do a quick check that all of your coax cable connections are in nice and "finger" tight - at the Hub and wall box and also at any connectors etc. Ensure there are no “unterminated cable loose ends. Disconnect all the connections and reconnect to be sure. Also check that the internal wiring is ok with no kinking or chaffing, check that all looks good with the outside cabling and wall box.
What do you get when connected on ethernet cable, and is that stable ?
If you think that you have a BB speed problem, then to check the speeds coming in to your Hub properly, and whether they match what you should be getting, you cannot rely on wifi tests, - no BB supplier guarantees those - only speeds "TO" the Hub are guaranteed. So, can you test speeds directly like this. As you expect >100Mbps then connect a 1GB enabled computer/laptop, with up to date drivers, via a known good and working Cat5e (or better) ethernet cable, directly to the Hub which you have put into “modem mode” (see VM website for “How To”). Test at speedtest.net (not using their App!) to your nearest VM server - try on 2 different browsers.
If they are still low – boot the device into safe+networking mode and try again.
There are many posts on here where unknown/flaky software, old network card drivers, corrupted browsers or other connected devices are limiting speeds on tests.
Report back what that gets.
-------------------- John --------------------
I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router +2 Airport Express's. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.