can i use two modems on single router?

[abdurrahman]

[Thunderoustoothbrush129]

No. Only one modem on your internet account.

[Luke Terrance]

That would be like saying can i build a house in a and on a house.
The modem is the account / router doing so would make it not work if you are having issues.
Try testing your internet getting a better isp getting a new router or using wired connection.

[Jim]

I can understand WHY this might be desirable - potentially twice the speed. Back in the days when normal phone lines were used for networking via telco, this used to be an option - but when speeds increased dramatically, this method was abandoned.