|Internet connection reliability and max speed being low problems like you describe are almost always caused by a problem with the high speed modem connection, not the router.|
It's not clear from your information whether you have a standalone high speed modem and a separate router, or a combo high speed modem/router. If you have a combo modem/router what I mention in the following about re-booting the modem applies to the combo, because the modem is built in.
- rebooting the modem
If it has a switch, turn it off, turn it on.
If it doesn't have a switch, uplug the power adapter connection at the modem, plug it back in.
Wait a short time until the leds indicate the modem has a good connection - you should then have a good connection to the internet.
- checking the connection of the coax cable to the modem and to whatever else it connects to, to make sure no connection is loose
- ( a) different coax cable(s)
- using a single longer coax cable rather than more than one connected in series
- if the coax cable is connected to a simple 2(or more) to 1 splitter box, try a different splitter box - one with gold plated connectors will be more reliable.
Gold plated connectors on the ends of the coax cable(s) are a lot less likely to cause problems due to an oxidization film forming on the connectors. You could try replacing the connectors on the ends of the coax cable(s) with gold plated ones if they're not gold plated.
I have a separate high speed modem and have used several different routers with it, wireless and wired. When I have had an internet connection problem, it's always been because of a problem with the modem's connection, not the router. Re-booting the modem usually fixes the problem right away.