This is not a question, this is an experience.
My name is Zer0Necrosis and I am a daddy, gamer and streamer. I use my internet for basically everything. I just want to warn users that although it is very easy to blame Comcast based on their track record and the fact that at one point they left a router exploit called "Cable Haunt '' unpatched for 3 months longer than they should have does not make them always the cause. One thing I would like to say is there are 3 major causes for speed drop.
OS and Ethernet / Wireless Settings - Settings inside your OS which controls your internet connectivity often through protocols and configurations. One big example is the setting in the "Network and Sharing Center '' in Windows 10. If you click on your "connections' ' typically called ethernet when wired and wireless when wireless; you will get a box. In that box you can then click on "properties'' and you will get another window. Now you simply click on the box called "configure" This will bring you to a window that says general and it will have some tabs. Left click on the tab labeled; "Advanced'' and scroll the properties box for an option called "Speed and Duplex" In most cases after selecting it if you look to the right you will a box called "value" and in the dropdown container the value will be "Auto Negotiation" in most cases this works fine. On some of my pcs this default value did not work so well; so if you manually set the value it can work far better. Simply left click the box and change the value to the speed you pay for which in my case is "1.0 Gbps Full Duplex '' and that fixes values.
OS Health - I know it is often easy to say; "Windows will fix itself." I have to say you are dead wrong. Anytime we use our pc no matter how good that part is, how fantastic the OS it will always need maintenance. If it's linux you will occasionally need to clear certain swap files but since I am mainly a windows 10 user with a history of never failing to solve an issue. I can say with certainty that you need to care for your system. If you or someone you trust does not know what you're doing even using an AOI is better than nothing. Advanced SystemCare Pro (Always Grab Latest) is an easy way to maintain a working pc. (Personally I like things a bit more hands on) Also make sure you use some kind of antivirus windows 10 has Defender built in but I find it does not listen when I tell it I want something allowed. It really is not too important. You need an adblock and a popup blocker extensions (System wide ones don't work well. You could do network wide for advanced users) or as my friends and I joke; "Internet Browser Protection" so you don't get an STI ``System Transmitted Infection"
Device Health - As long as you live all things around you can and will collect dust and grime. Your pc, router, modem, ethernet switch they all produce heat and a slight pull when it comes to dust etc. If you don't understand this you should not own an electronic because a dusty machine can catch fire. Also from time to time no matter how annoying maybe once a month power cycle your devices. All of them. I recommend using an easy to reach surge protector.
Bit Defender box2 - It is a very powerful device but sometimes giving it a 20 second break at least once a month brings your speed from 20% to 110% If you own a Bitdefender Box make sure your room its in does not exceed 72 degrees because most electronics have about a 30 degrees increase internally with a short circuit point of 145 - 165 degrees.
Final Notes - If none of these issues work simply ask for a tech to come out because it means you have done everything and something is broken that is not in your control. Also always make sure your hardware wires etc are up to standard for the service you are paying for. If you only pay for 200 mbps then as long as your equipment can reach that you should be fine. Thanks for reading.