Internet connection coming and going I have Xfinity internet 600Mbps

The ISP (Comcast) technician did say it was a signal problem when he went on Friday January 28,2022 and was told by the tech that he fixed that problem.I forgot to mention I have a AC750 WiFi Range Extender (EX3700) It is near the backyard door not near the cable modem/router could this be an issue?I have this bcause my house is about 1,300Sq.FT it is a one story home, I am not currently home so I can't post the modems connection status page but I will do that once I get home I did call my mom and she says that the Internet is currently working. I checked that there are no coax cable line splitters in the between the modem and ISP service box, Iam  using good quality RG6 coax cable up to the modem because that was installed by Comcast I've had Comcast sine November so the coax cable is fairly new. In the event log I uploaded there was a T4 timeout at the top what exactly does that mean?