How do I open ports on an Actiontec MI424WR?

Question

Visiting a friend who has Frontier FiOS internet and an Actiontec MI424WR broadband router, latest version. While their ethernet connection works for web browsing, they are experiencing what I believe are firewall-related issues connecting to:

Inbound POP and IMAP ports 995, 993 via wifi mobile devices attempting to access imap.gmail.com and pop.gmail.com; and

Outbound POP and IMAP ports 465 (SSL) and 587 and 995 at pop.gmail.com and imap.gmail.com; and

Ethernet connection to Xbox Live; and

Ethernet connection to Hulu.com service via ROKU 2 XS.

My sense is that the fix is as simple as accessing the admin panel at 192.168.1.1 and creating allow rules in the firewall settings; or, to use port-forwarding allow rules; however my experience in these areas on a router - or rather this particular router - is somewhat limited.

I could use some help or recommendations on:

1. Whether this is likely an issue requiring the creation of a port-forwarding rule or an allow rule in the firewall and;

2. Whether the rule should be TCP, UDP or BOTH and based on the port or ... ?

I've already explored tech support at Frontier and apparently once you get into the firewall, they are "not allowed" to help you but rather are instructed to upsell you on paid support product offering.

I've already spoken with Google and confirmed that it is not an issue on their end, but likely simply an overtly aggressive firewall setting that needs some exceptions added.

I've also already confirmed that it is THIS router and THIS wifi, as mobile devices ARE able to successfully make these port connections via cellular-only service as well as other wifi networks.

So I've narrowed it down to the router firewall or port-forwarding settings.