Hi. I've got a 350mb package which I've had for 5 years. I have suffered constant drop outs and never go a week without problems. I paid to have most items in the house connected by Ethernet and 2 x ubiquity routers fitted for Wi-Fi. Still the same problems. Engineer came out eventually and said we were getting 90 MB and didn't know why we weren't getting near what we are paying for. He mentioned throttling. I've tested regularly at 20mb. He said he would escalate and we never heard back. Anyone getting same issues? We've given up now and just put up with it.
If your is a Hub 3/4/5 in Router mode you can easily test the performance to the Hub and the devices using this link : https://www.samknows.com/realspeed/
For the test to the Hub we are expecting to see a result that reflects the M350.
For the laptops / mobiles how they are connected and their software packages all affect the results