[Dovecot] IMAP connection timeout value?

So we're having some ISP issues lately, meaning we have to reboot our cable modem like 2-3 times a day. An unfortunate side-effect I've found is, once the users max out their connection limit (which I've set to 10, and many people do), if we reboot the cable modem, they can't log in cause their connections get 'stuck' until I doveadm kick them, or wait for the connections to timeout which takes ??? minutes. Can I adjust that value to something like 30 seconds?

Thanks and best regards, KT