Connect error 2.3.2 client to 2.6.12 server

[bibaboba]

Hello! I have OpenVPN server ver. 2.6.12. With OpenVPN Connect and newest Asus's VPN Fusion clients all works perfectly. I have some old Asus routers, that have OpenVPN client 2.3.2 onboard. When I try to connect them to the server using the existing working .ovpn files, I get this error. The routers have the latest firmware. I can't replace these routers, I need to ensure their connection to the server. Thank you!

Client log

Oct 13 14:56:56 rc_service: httpd 195:notify_rc restart_vpncall
Oct 13 14:57:00 rc_service: httpd 195:notify_rc restart_vpncall
Oct 13 14:57:00 openvpn[4967]: OpenVPN 2.3.2 mipsel-unknown-linux-gnu [SSL (OpenSSL)] [LZO] [EPOLL] [eurephia] [MH] [IPv6] built on Aug 17 2018
Oct 13 14:57:00 openvpn[4967]: Cipher algorithm 'AES-128-GCM' not found (OpenSSL)
Oct 13 14:57:00 openvpn[4967]: Exiting due to fatal error

Server cofig

cd /etc/openvpn/server
mode server
proto udp
port 50443
dev-type tun
dev antizapret-udp
topology subnet
server 10.29.0.0 255.255.252.0
push "route 10.30.0.0 255.254.0.0"
push "dhcp-option DNS 10.29.0.1"
push "block-outside-dns"
cipher AES-128-GCM
txqueuelen 1000
keepalive 15 30
persist-tun
persist-key
fast-io
user nobody
duplicate-cn
#log logs/antizapret-udp.log
status logs/antizapret-udp-status.log 30
client-config-dir ccd
ca keys/ca.crt
cert keys/antizapret-server.crt
key keys/antizapret-server.key
dh keys/dh2048.pem
crl-verify keys/crl.pem

.ovpn config

nobind
client
remote *.*.*.* 50443 udp
remote *.*.*.* 443 udp
server-poll-timeout 10
remote-cert-tls server
dev tun
cipher AES-128-GCM
resolv-retry infinite
persist-key
persist-tun
setenv FRIENDLY_NAME "AntiZapret *.*.*.* UDP"

# Keys
<ca>
-----BEGIN CERTIFICATE-----
***
-----END CERTIFICATE-----
</ca>

<cert>
-----BEGIN CERTIFICATE-----
***
-----END CERTIFICATE-----
</cert>

<key>
-----BEGIN PRIVATE KEY-----
***
-----END PRIVATE KEY-----
</key>
​