My wifi for the last two months straight its like someone is turning it off and on with a switch

Hello All,

I have had now almost 8 techs out here and three line guys for the pole, they have replaced every single thing in my hous elike 5 times already nothing is working. What happens is my internet goes on and off intermittently during day and really bad all night. They say everytime lets replace modem etc which they do everytime or they fix something on pole and say dont worry now fixed however I keep having the same issues now the 9th person will be out here on minday im sure trying to replace a modem again which it has been replaced almost 8 times now. Now they say again oh we found th eproblem but its still doing it. Also I need to mention that when it does come back on I have 400 mbps and and it will say I am only getting 40-60 mbps. Then very rare and usually during the day Ill get 400? I am at my wits end I work from home obviously per covid and I am about to loose my job because of this internet problem plus its raising my blood pressure i talk to them everyday xfinity on phone and talk to techs and line guys nothing is working??? I found the forum and found someone who had similiar issues and he said finally after months the tech guy didnt think it would work but when he (capped a port) or something like that it stopped happening and the guy hasnt had issues since so I am going to askt hem when they come out againf or the 9th time in two months i hope on monday and has anyone had this issue and if so how did they fix it I am about to loos emy mind over here and my job and this is nuts I am like do i switch to soemone else this is terrible plus there still billing me full bills ???? HELP@everyone